Organic compound, organic light emitting diode and organic light emitting device having the compound

ABSTRACT

Disclosed is an organic compound that includes a fused hetero aromatic moiety of a spiro structure as an electron donor and a triazine moiety as an electron acceptor that is linked to the electron donor via an arylene linker substituted with at least one electron withdrawing group, an organic light emitting diode and an organic light emitting device each of which applies the organic compound into at least one emitting unit. The organic compound enables the organic light emitting diode to increase its luminous efficiency and to improve its color purity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(a) of KoreanPatent Application No. 10-2018-0168347, filed in the Republic of Koreaon Dec. 24, 2018, which is incorporated herein by reference in itsentirety.

BACKGROUND Technical Field

The present disclosure relates to an organic compound, and morespecifically, to an organic compound having enhanced luminousefficiency, an organic light emitting diode and an organic lightemitting device including the organic compound.

Description of the Related Art

As display devices have become larger, there exists a need for flatdisplay devices that occupy less space. Among the flat display devices,a display device using an organic light emitting diode (OLED) has comeinto the spotlight.

In the OLED, when electrical charges are injected into an emission layerbetween an electron injection electrode (i.e., cathode) and a holeinjection electrode (i.e., anode), electrical charges are combined to bepaired, and then emit light as the combined electrical charges aredisappeared.

The OLED can be formed even on a flexible transparent substrate such asa plastic substrate. In addition, the OLED can be driven at a lowervoltage of 10 V or less. Besides, the OLED has relatively low powerconsumption for driving compared to plasma display panels and inorganicelectroluminescent devices, and a color purity thereof is very high.Further, since the OLED can display various colors such as green, blue,red and the like, the OLED display device has attracted a lot ofattention as a next-generation display device that can replace a liquidcrystal display device (LCD).

BRIEF SUMMARY

Accordingly, the present disclosure is directed to an organic compound,an organic light emitting diode and an organic light emitting deviceincluding the organic compound that can reduce one or more of theproblems due to the limitations and disadvantages of the related art.

An object of the present disclosure is to provide an organic compoundthat has enhanced luminous efficiency, and an organic light emittingdiode and an organic light emitting device each of which includes theorganic compound in an emitting unit.

Another object of the present disclosure is to provide an organiccompound with improved color purity, and an organic light emitting diodeand an organic light emitting device each of which includes the organiccompound in an emitting unit.

Additional features and advantages of the disclosure will be set forthin the description which follows, and in part will be apparent from thedescription, or may be learned by practice of the disclosure. Theobjectives and other advantages of the disclosure will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

According to an aspect, the present disclosure provides an organiccompound having the following Chemical Formula 1:

wherein each of R₁ to R₅ is independently protium, deuterium, tritium,halogen, C₁˜C₁₀ alkyl halide, cyano group, nitro group or a moietyhaving the following structure of Chemical Formula 2 or Chemical Formula3, wherein at least one of R₁ to R₅ is selected from the groupconsisting of halogen, C₁˜C₁₀ alkyl halide, cyano group and nitro groupand at least one of R₁ to R₅ is a moiety of Chemical Formula 2 orChemical Formula 3; each of R₆ and R₇ is independently C₅˜C₃₀ aryl groupor C₄˜C₃₀ hetero aryl group:

wherein each of R₈ and R₉ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ aryl group, C₄˜C₃₀ hetero arylgroup, C₅˜C₃₀ aryl amino group and C₄˜C₃₀ hetero aryl amino group,wherein each of the C₅˜C₃₀ aryl group, the C₄˜C₃₀ hetero aryl group, theC₅˜C₃₀ aryl amino group and the C₄˜C₃₀ hetero aryl amino group isunsubstituted or substituted with an aromatic group, a hetero aromaticgroup or a combination thereof, respectively; each of a and b is anumber of a substituent and is independently an integer of 1 to 3; X inChemical Formula 3 is CR₁₁R₁₂, NR₁₃, SiR₁₄R₁₅, oxygen (O) or sulfur (S),wherein each of R₁₁ to R₁₅ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ aryl group and C₄˜C₃₀ heteroaryl group.

According to another aspect, the present disclosure provides an organiclight emitting diode (OLED) that comprises a first electrode; a secondelectrode facing the first electrode; and at least one emitting unitincluding an emitting material layer disposed between the first andsecond electrodes, wherein the emitting material layer comprises theabove organic compound.

According to still another aspect, the present disclosure provides anorganic light emitting device that comprises a substrate and the OLEDdisposed over the substrate, as described above.

It is to be understood that both the foregoing general description andthe following detailed description are examples and are explanatory andare intended to provide further explanation of the disclosure asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure, are incorporated in and constitute apart of this specification, illustrate implementations of the disclosureand together with the description serve to explain the principles ofembodiments of the disclosure.

FIG. 1 is a schematic cross-sectional view illustrating an organic lightemitting display device of the present disclosure.

FIG. 2 is a schematic cross-sectional view illustrating an organic lightemitting diode in accordance with an exemplary embodiment of the presentdisclosure.

FIG. 3 is a schematic diagram illustrating a luminous mechanism of thedelayed fluorescent material in an EML in accordance with an exemplaryembodiment of the present disclosure.

FIG. 4 is a schematic diagram illustrating a luminous mechanism byenergy level bandgaps between luminous materials in accordance with anexemplary embodiment of the present disclosure.

FIG. 5 is a schematic cross-sectional view illustrating an organic lightemitting diode in accordance with another exemplary embodiment of thepresent disclosure.

FIG. 6 is a schematic diagram illustrating a luminous mechanism byenergy level bandgaps among luminous materials in accordance withanother exemplary embodiment of the present disclosure.

FIG. 7 is a schematic cross-sectional view illustrating an organic lightemitting diode in accordance with another exemplary embodiment of thepresent disclosure.

FIG. 8 is a schematic diagram illustrating a luminous mechanism byenergy level bandgaps among luminous materials in accordance withanother exemplary embodiment of the present disclosure.

FIG. 9 is a schematic cross-sectional view illustrating an organic lightemitting diode in accordance with another exemplary embodiment of thepresent disclosure.

FIG. 10 is a schematic diagram illustrating a luminous mechanism byenergy level bandgaps among luminous materials in accordance withanother exemplary embodiment of the present disclosure.

FIG. 11 is a schematic cross-section view illustrating an organic lightemitting diode in accordance with another exemplary embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to aspects of the disclosure,examples of which are illustrated in the accompanying drawings.

Organic Compound

An organic compound included in an organic light emitting diode shouldhave excellent luminous properties and maintain stable properties duringdriving the diode. An organic compound of the present disclosure has afused hetero aromatic moiety of a spiro structure as an electron donorand a triazine moiety as an electron acceptor which is bonded to theelectron donor via an aromatic linker group. The organic compound of thepresent disclosure has the following structure of Chemical Formula 1:

In Chemical Formula 1, each of R₁ to R₅ is independently protium,deuterium, tritium, halogen, C₁˜C₁₀ alkyl halide, cyano group, nitrogroup or a moiety having the following structure of Chemical Formula 2or Chemical Formula 3. At least one of R₁ to R₅ is selected from thegroup consisting of halogen, C₁˜C₁₀ alkyl halide, cyano group and nitrogroup. At least one of R₁ to R₅ is a moiety of Chemical Formula 2 orChemical Formula 3. Each of R₆ and R₇ is independently C₅˜C₃₀ aryl groupor C₄˜C₃₀ hetero aryl group:

In Chemical Formulae 2 and 3, each of R₈ and R₉ is independentlyselected from the group consisting of protium, deuterium, tritium,C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ arylgroup, C₄˜C₃₀ hetero aryl group, C₅˜C₃₀ aryl amino group and C₄˜C₃₀hetero aryl amino group, wherein each of the C₅˜C₃₀ aryl group, theC₄˜C₃₀ hetero aryl group, the C₅˜C₃₀ aryl amino group and the C₄˜C₃₀hetero aryl amino group is unsubstituted or substituted with an aromaticgroup, a hetero aromatic group or a combination thereof, respectively.Each of a and b is a number of a substituent and is independently aninteger of 1 to 3. X in Chemical Formula 3 is CR₁₁R₁₂, NR₁₃, SiR₁₄R₁₅,oxygen (O) or sulfur (S), wherein each of R₁₁ to R₁₅ is independentlyselected from the group consisting of protium, deuterium, tritium,C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ arylgroup and C₄˜C₃₀ hetero aryl group.

As used herein, the term “unsubstituted” means that hydrogen atom isbonded, and in this case hydrogen atom includes protium, deuterium andtritium.

As used herein the term “substituent” may include, but is not limitedto, C₁˜C₂₀ alkyl group unsubstituted or substituted with halogen, C₁˜C₂₀alkoxy group unsubstituted or substituted with halogen, halogen, cyanogroup, —CF₃, hydroxyl group, carboxyl group, carbonyl group, aminogroup, C₁˜C₂₀ alkyl amino group, C₅˜C₃₀ aryl amino group, C₄˜C₃₀ heteroaryl amino group, nitro group, hydrazyl group, sulfonyl group, C₅˜C₃₀alkyl silyl group, C₅˜C₃₀ alkoxy silyl group, C₃˜C₃₀ cycloalkyl silylgroup, C₅˜C₃₀ aryl silyl group. C₄˜C₃₀ hetero aryl silyl group, C₅˜C₃₀aryl group and C₄˜C₃₀ hetero aryl group. As an example, when each of R₁to R₆ is independently substituted with alkyl group, the alkyl group maybe linear or branched C₁˜C₂₀ alkyl group, and preferably linear orbranched C₁˜C₁₀ alkyl group.

As used herein, the term “hetero” described in “hetero aromatic ring”,“hetero aromatic group”, “hetero alicyclic ring”, “hetero cyclic alkylgroup”, “hetero aryl group”, “hetero aralkyl group”, “hetero aryloxylgroup”, “hetero aryl amino group”, “hetero arylene group”, “heteroaralkylene group”, “hetero aryloxylene group”, and the like means thatat least one carbon atoms, for example 1 to 5 carbon atoms, forming sucharomatic or alicyclic rings are substituted with at least one heteroatoms selected from the group consisting of N, O, S and combinationthereof.

In one exemplary embodiment, when each of R₆ and R₇ in Chemical Formula1, R₈, R₉ and R₁₁ to R₁₅ in Chemical Formulae 2 and 3 and an aromaticgroup substituted with those groups is an aromatic substituent such asC₅˜C₃₀ aryl group, the aromatic substituent may independently include,but is not limited to, unfused or fused aryl group such as phenyl,biphenyl, terphenyl, naphthyl, anthracenyl, pentalenyl, indenyl,indeno-indenyl, heptaleneyl, biphenylenyl, indacenyl, phenalenyl,phenanthrenyl, benzo-phenanthrenyl, dibenzo-phenanthrenyl, azulenyl,pyreneyl, fluoranthenyl, triphenylenyl, chrysenyl, tetraphenyl,tetracenyl, pleiadenyl, picenyl, pentaphenyl, pentacenyl, fluorenyl,indeno-fluorenyl or spiro-fluorenyl.

In an alternative embodiment, when each of R₆ and R₇ in Chemical Formula1, R₈, R₉ and R₁₁ to R₁₅ in Chemical Formulae 2 and 3 and an aromaticgroup substituted with those groups is a hetero aromatic substituentsuch as C₄˜C₃₀ hetero aryl group, the hetero aromatic substituent mayindependently include, but is not limited to, unfused or fused heteroaryl group such as furanyl, thiophenyl, pyrrolyl, pyridinyl,pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, tetrazinyl, imidazolyl,pyrazolyl, indolyl, carbazolyl, benzo-carbazolyl, dibenzo-carbazolyl,indolo-carbazolyl, indeno-carbazolyl, benzofuro-carbazolyl,benzothieno-carbazolyl, quinolinyl, iso-quinolinyl, phthalazinyl,quinoxalinyl, cinnolinyl, quinazolinyl, benzo-quinolinyl,benzo-iso-quinolinyl, benzo-quinazolinyl, benzo-quinoxalinyl, acridinyl,phenanthrolinyl, phenazinyl, phenoxazinyl, phenothiazinyl, pyranyl,oxazinyl, oxazolyl, iso-oxazolyl, oxadiazolyl, triazolyl, dioxinyl,benzo-furanyl, dibenzo-furanyl, thiopyranyl, thiazinyl,benzo-thiophenyl, dibenzo-thiophenyl, spiro-acridinyl connected to axanthene, dihydro-acridinyl substituted with at least one C₁˜C₁₀ alkylgroup and N-substituted spiro-fluorenyl.

The organic compound having the structure of Chemical Formula 1 includesa fused hetero aromatic moiety of spiro structure having a nitrogen atomas an electron donor and a triazine moiety linked to the electron donormoiety via a phenylene linker. As a streric hindrance between theelectron donor and the electron acceptor increases, dihedral anglesbetween those moieties increases. As a result, the organic compound canbe divided easily into a highest occupied molecular orbital (HOMO)energy state and a lowest unoccupied molecular orbital (LUMO) energystate because the formation of the conjugate structure between thosemoieties is limited.

In addition, dipoles are formed between the electron donor moiety andthe electron acceptor moiety, and the dipole moments within the moleculeare increased. Therefore, an organic light emitting diode using theorganic compound can enhance its luminous efficiency. Moreover, theorganic compound has a limited conformational structure owing to thefused hetero aromatic moiety of the spiro structure with a large sterichindrance. As a result, when the organic compound having the structureof Chemical Formula 1 is laminated, the conformational structure of theorganic compound is not changed, so the energy loss during theluminescent process is reduced and the luminescence spectrum of theorganic compound can be limited to a specific range to improve its colorpurity. As the luminous efficiency of an OLED using the organic compoundis improved, it is not necessary to increase a driving voltage of theOLED. Moreover, power consumption of the OLED and load applied to theOLED, each of which is increased as the driving voltage, can be reduced,so that the luminous lifetime of the OLED can be increased.

In one exemplary embodiment, the organic compound having the structureof Chemical Formula 1 may have one cyano group on the central phenylenelinker. Such an organic compound may have the following structure ofChemical Formula 4:

In Chemical Formula 4, R₂₁ is cyano group. R₂₂ is a moiety having thefollowing structure of Chemical Formula 5 or Chemical Formula 6:

In Chemical Formulae 5 and 6, each of R₂₃ and R₂₄ is independentlyselected from the group consisting of protium, deuterium, tritium,C₁˜C₂₀ alkyl group, C₅˜C₃₀ aryl group unsubstituted or substituted witharomatic group, hetero aromatic group or combination thereof and C₄˜C₃₀hetero aryl group unsubstituted or substituted with aromatic group,hetero aromatic group or combination thereof. X in Chemical Formula 6 isCR₁₁R₁₂, NR₁₃, SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁to R₁₅ is independently selected from the group consisting of protium,deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀silyl group, C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.

Particularly, the organic compound having one cyano group on thephenylene linker may have any one of the following structures ofChemical Formula 7.

In another exemplary embodiment, the organic compound having thestructure of Chemical Formula 1 may have two cyano groups on the centralphenylene linker. Such an organic compound may have the followingstructure of Chemical Formula 8:

In Chemical Formula 8, each of R₃₁ and R₃₂ is cyano group. R₃₃ is amoiety having the following structure of Chemical Formula 9 or ChemicalFormula 10:

In Chemical Formulae 9 and 10, each of R₃₄ and R₃₅ is independentlyselected from the group consisting of protium, deuterium, tritium,C₁˜C₂₀ alkyl group, C₅˜C₃₀ aryl group unsubstituted or substituted witharomatic group, hetero aromatic group or combination thereof and C₄˜C₃₀hetero aryl group unsubstituted or substituted with aromatic group,hetero aromatic group or combination thereof. X in Chemical Formula 9 isCR₁₁R₁₂, NR₁₃, SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁to R₁₅ is independently selected from the group consisting of protium,deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀silyl group, C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.

Particularly, the organic compound having two cyano groups on thephenylene linker may have any one of the following structures ofChemical Formula 11.

[Organic Light Emitting Device]

The organic compound having the structure of any one in ChemicalFormulae 1, 4, 7, 8 and 11 has a delayed fluorescent property owing toco-existence of the electron donor moiety and the electron acceptormoiety within the molecule. The organic compound having the structure ofany one in Chemical Formulae 1, 4, 7, 8 and 11 may be applied to anemitting material layer of an organic light emitting diode so as toimplement an organic light emitting element having enhanced luminousefficiency and lower driving voltage.

The organic light emitting diode of the present disclosure may beapplied to an organic light emitting device such as an organic lightemitting display device and an organic light emitting illuminationdevice. An organic light emitting display device will be explained. FIG.1 is a schematic cross-sectional view of an organic light emittingdisplay device in accordance with an exemplary embodiment of the presentdisclosure.

As illustrated in FIG. 1, the organic light emitting display device 100includes a substrate 102, a thin-film transistor Tr on the substrate102, and an organic light emitting diode 200 connected to the thin filmtransistor Tr.

The substrate 102 may include, but is not limited to, glass, thinflexible material and/or polymer plastics. For example, the flexiblematerial may be selected from the group, but is not limited to,polyimide (PI), polyethersulfone (PES), polyethylenenaphthalate (PEN),polyethylene terephthalate (PET), polycarbonate (PC) and combinationthereof. The substrate 102, over which The thin film transistor Tr andthe organic light emitting diode 200 are arranged, form an arraysubstrate.

A buffer layer 104 may be disposed over the substrate 102, and the thinfilm transistor Tr is disposed over the buffer layer 104. The bufferlayer 104 may be omitted.

A semiconductor layer 110 is disposed over the buffer layer 104. In oneexemplary embodiment, the semiconductor layer 110 may include, but isnot limited to, oxide semiconductor materials. In this case, alight-shield pattern may be disposed under the semiconductor layer 110,and the light-shield pattern can prevent light from being incidenttoward the semiconductor layer 110, and thereby, preventing thesemiconductor layer 110 from being deteriorated by the light.Alternatively, the semiconductor layer 110 may include, but is notlimited to, polycrystalline silicon. In this case, opposite edges of thesemiconductor layer 110 may be doped with impurities.

A gate insulating layer 120 formed of an insulating material is disposedon the semiconductor layer 110. The gate insulating layer 120 mayinclude, but is not limited to, an inorganic insulating material such assilicon oxide (SiO_(x)) or silicon nitride (SiN_(x)).

A gate electrode 130 made of a conductive material such as a metal isdisposed over the gate insulating layer 120 so as to correspond to acenter of the semiconductor layer 110. While the gate insulating layer120 is disposed over a whole area of the substrate 102 in FIG. 1, thegate insulating layer 120 may be patterned identically as the gateelectrode 130.

An interlayer insulating layer 140 formed of an insulating material isdisposed on the gate electrode 130 with covering over an entire surfaceof the substrate 102. The interlayer insulating layer 140 may include,but is not limited to, an inorganic insulating material such as siliconoxide (SiO_(x)) or silicon nitride (SiN_(x)), or an organic insulatingmaterial such as benzocyclobutene or photo-acryl.

The interlayer insulating layer 140 has first and second semiconductorlayer contact holes 142 and 144 that expose both sides of thesemiconductor layer 110. The first and second semiconductor layercontact holes 142 and 144 are disposed over opposite sides of the gateelectrode 130 with spacing apart from the gate electrode 130. The firstand second semiconductor layer contact holes 142 and 144 are formedwithin the gate insulating layer 120 in FIG. 1. Alternatively, the firstand second semiconductor layer contact holes 142 and 144 are formed onlywithin the interlayer insulating layer 140 when the gate insulatinglayer 120 is patterned identically as the gate electrode 130.

A source electrode 152 and a drain electrode 154, each of which is madeof a conductive material such as a metal, are disposed on the interlayerinsulating layer 140. The source electrode 152 and the drain electrode154 are spaced apart from each other with respect to the gate electrode130, and contact both sides of the semiconductor layer 110 through thefirst and second semiconductor layer contact holes 142 and 144,respectively.

The semiconductor layer 110, the gate electrode 130, the sourceelectrode 152 and the drain electrode 154 constitute the thin filmtransistor Tr, which acts as a driving element. The thin film transistorTr in FIG. 1 has a coplanar structure in which the gate electrode 130,the source electrode 152 and the drain electrode 154 are disposed overthe semiconductor layer 110. Alternatively, the thin film transistor Trmay have an inverted staggered structure in which a gate electrode isdisposed under a semiconductor layer and a source and drain electrodesare disposed over the semiconductor layer. In this case, thesemiconductor layer may comprise amorphous silicon.

A gate line and a data line, which cross each other to define a pixelregion, and a switching element, which is connected to the gate line andthe data line is, may be further formed in the pixel region. Theswitching element is connected to the thin film transistor Tr, which isa driving element. Additionally, a power line is spaced apart inparallel from the gate line or the data line, and the thin filmtransistor Tr may further include a storage capacitor configured toconstantly keep a voltage of the gate electrode for one frame.

In addition, the organic light emitting display device 100 may include acolor filter for absorbing a part of the light emitted from the organiclight emitting diode 200. For example, the color filter may absorb alight of specific wavelength such as red (R), green (G) or blue (B). Inthis case, the organic light emitting display device 100 can implementfull-color through the color filter.

For example, when the organic light emitting display device 100 is abottom-emission type, the color filter may be disposed on the interlayerinsulating layer 140 with corresponding to the organic light emittingdiode 200. Alternatively, when the organic light emitting display device100 is a top-emission type, the color filter may be disposed over theorganic light emitting diode 200, that is, above a second electrode 220.

A passivation layer 160 is disposed on the source and drain electrodes152 and 154 over the whole substrate 102. The passivation layer 160 hasa flat top surface and a drain contact hole 162 that exposes the drainelectrode 154 of the thin film transistor Tr. While the drain contacthole 162 is disposed on the second semiconductor layer contact hole 154,it may be spaced apart from the second semiconductor layer contact hole154.

The organic light emitting diode 200 includes a first electrode 210 thatis disposed on the passivation layer 160 and connected to the drainelectrode 154 of the thin film transistor Tr. The organic light emittingdiode 200 further includes an emitting unit 230 as an emission layer anda second electrode 220 each of which is disposed sequentially on thefirst electrode 210.

The first electrode 210 is disposed in each pixel region. The firstelectrode 210 may be an anode and include a conductive material having arelatively high work function value. For example, the first electrode210 may include, but is not limited to, a transparent conductivematerial such as indium tin oxide (ITO), indium zinc oxide (IZO), indiumtin zinc oxide (ITZO), tin oxide (SnO), zinc oxide (ZnO), indium ceriumoxide (ICO), aluminum doped zinc oxide (AZO), and the like.

In one exemplary embodiment, when the organic light emitting displaydevice 100 is a top-emission type, a reflective electrode or areflective layer may be disposed under the first electrode 210. Forexample, the reflective electrode or the reflective layer may include,but is not limited to, aluminum-palladium-copper (APC) alloy.

In addition, a bank layer 170 is disposed on the passivation layer 160in order to cover edges of the first electrode 210. The bank layer 170exposes a center of the first electrode 210.

An emitting unit 230 is disposed on the first electrode 210. In oneexemplary embodiment, the emitting unit 230 may have a mono-layeredstructure of an emitting material layer. Alternatively, the emittingunit 230 may have a multiple-layered structure of a hole injectionlayer, a hole transport layer, an electron blocking layer, an emittingmaterial layer, a hole blocking layer, an electron transport layerand/or an electron injection layer (See, FIGS. 2, 5, 7, 9 and 11). Inone embodiment, the organic light emitting diode 200 may have oneemitting unit 230. Alternatively, the organic light emitting diode 200may have multiple emitting units 230 to form a tandem structure. Theemitting unit 230 includes an organic compound having the structure ofany one in Chemical Formulae 1, 4, 7, 8 and 11. As an example, theorganic compound having the structure of any one in Chemical Formulae 1,4, 7, 8 and 11 may be used a dopant of an emitting material layer whichmay further includes at least one host.

The second electrode 220 is disposed over the substrate 102 above whichthe emitting unit 230 is disposed. The second electrode 220 may bedisposed over a whole display area and may include a conductive materialwith a relatively low work function value compared to the firstelectrode 210. The second electrode 220 may be a cathode. For example,the second electrode 220 may include, but is not limited to, aluminum(Al), magnesium (Mg), calcium (Ca), silver (Ag), alloy thereof orcombination thereof such as aluminum-magnesium alloy (Al—Mg).

In addition, an encapsulation film 180 may be disposed over the secondelectrode 220 in order to prevent outer moisture from penetrating intothe organic light emitting diode 200. The encapsulation film 180 mayhave, but is not limited to, a laminated structure of a first inorganicinsulating film 182, an organic insulating film 184 and a secondinorganic insulating film 186.

The emitting unit 230 of the OLED 200 includes the organic compoundhaving the structure of any one in Chemical Formulae 1, 4, 7, 8 and 11,as described above. Since the organic compound has both an electrondonor moiety and an electron acceptor moiety, the organic compoundexhibits a delayed fluorescent property. The OLED 200 can enhance itsluminous efficiency and lower its driving voltage so as to reduce itsconsumption power by applying the organic compound having the structureof any one in Chemical Formulae 1, 4, 7, 8 and 11 into the emitting unit230.

[Organic Light Emitting Diode]

FIG. 2 is a schematic cross-sectional view illustrating an organic lightemitting diode in accordance with an exemplary embodiment of the presentdisclosure. As illustrated in FIG. 2, the organic light emitting diode(OLED) 300 in accordance with the first embodiment of the presentdisclosure includes first and second electrodes 310 and 320 facing eachother, an emitting unit 330 as an emission layer disposed between thefirst and second electrodes 310 and 320. In one exemplary embodiment,the emitting unit 330 include a hole injection layer (HIL) 340, a holetransport layer (HTL) 350, an emitting material layer (EML) 360, anelectron transport layer (ETL) 370 and an electron injection layer (EIL)380 each of which is laminated sequentially from the first electrode310. Alternatively, the emitting unit 330 may further include a firstexciton blocking layer, i.e. an electron blocking layer (EBL) 355disposed between the HTL 350 and the EML 360 and/or a second excitonblocking layer. i.e. a hole blocking layer (HBL) 375 disposed betweenthe EML 360 and the ETL 370.

The first electrode 310 may be an anode that provides a hole into theEML 360. The first electrode 310 may include, but is not limited to, aconductive material having a relatively high work function value, forexample, a transparent conductive oxide (TCO). In an exemplaryembodiment, the first electrode 310 may include, but is not limited to,ITO, IZO, ITZO, SnO, ZnO, ICO, AZO, and the like.

The second electrode 320 may be a cathode that provides an electron intothe EML 360. The second electrode 320 may include, but is not limitedto, a conductive material having a relatively low work function values,i.e., a highly reflective material such as Al, Mg, Ca, Ag, alloythereof, combination thereof, and the like. As an example, each of thefirst and second electrodes 310 and 320 may be laminated with athickness of, but not limited to, about 30 nm to about 300 nm.

The HIL 340 is disposed between the first electrode 310 and the HTL 350and improves an interface property between the inorganic first electrode310 and the organic HTL 350. In one exemplary embodiment, the HIL 340may include, but is not limited to,4,4′4″-Tris(3-methylphenylamino)triphenylamine (MTDATA),4,4′,4″-Tris(N,N-diphenyl-amino)triphenylamine (NATA),4,4′,4″-Tris(N-(naphthalene-1-yl)-N-phenyl-amino)triphenylamine(1T-NATA),4,4′,4″-Tris(N-(naphthalene-2-yl)-N-phenyl-amino)triphenylamine(2T-NATA), Copper phthalocyanine (CuPc),Tris(4-carbazoyl-9-yl-phenyl)amine (TCTA),N,N′-Diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4″-diamine (NPB;NPD), 1,4,5,8,9,11-Hexaazatriphenylenehexacarbonitrile(Dipyrazino[2,3-f:2′3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile;HAT-CN), 1,3,5-tris[4-(diphenylamino)phenyl]benzene (TDAPB),poly(3,4-ethylenedioxythiphene)polystyrene sulfonate (PEDOT/PSS) and/orN-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine.The HIL 340 may be omitted in compliance with a structure of the OLED300.

The HTL 350 is disposed adjacently to the EML 360 between the firstelectrode 310 and the EML 360. In one exemplary embodiment, the HTL 350may include, but is not limited to,N,N′-Diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD),NPB, 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP),Poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)-benzidine] (Poly-TPD),Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine))](TFB), Di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane (TAPC),N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amineand/orN-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine.

In one exemplary embodiment, each of the HIL 340 and the HTL 350 may belaminated with a thickness of, but is not limited to, about 5 nm toabout 200 nm, and preferably about 5 nm to about 100 nm.

The EML 360 may include a host doped with a dopant where a substantiallight emission is occurred. In this exemplary embodiment, the EML 360may include a host (a first host) doped with a dopant (a first dopant).For example, the organic compound having the structure of any one inChemical Formulae 1, 4, 7, 8 and 11 may be used as a delayed fluorescentdopant (dopant 1 or T dopant) in the EML 360. The EML 360 may emit lightof green color. The configuration and energy levels among the luminousmaterials in the EML 360 will be explained in more detail.

The ETL 370 and the EIL 380 are laminated sequentially between the EML360 and the second electrode 320. The ETL 370 may include a materialhaving high electron mobility so as to provide electrons stably with theEML 360 by fast electron transportation.

In one exemplary embodiment, the ETL 370 may include, but is not limitedto, oxadiazole-based compounds, triazole-based compounds,phenanthroline-based compounds, benzoxazole-based compounds,benzothiazole-based compounds, benzimidazole-based compounds,triazine-based compounds, and the like.

As an example, the ETL 370 may include, but is not limited to,tris-(8-hydroxyquinoline aluminum (Alq₃),2-biphenyl-4-yl-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD), spiro-PBD,lithium quinolate (Liq), 1,3,5-Tris(N-phenylbenzimidazol-2-yl)benzene(TPBi),Bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-biphenyl-4-olato)aluminum(BAlq), 4,7-diphenyl-1,10-phenanthroline (Bphen),2,9-Bis(naphthalene-2-yl)4,7-diphenyl-1,10-phenanthroline (NBphen),2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP),3-(4-Biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ),4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ),1,3,5-Tri(p-pyrid-3-yl-phenyl)benzene (TpPyPB),2,4,6-Tris(3′-(pyridin-3-yl)biphenyl-3-yl)1,3,5-triazine (TmPPPyTz),Poly[9,9-bis(3′-(N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene]-alt-2,7-(9,9-dioctylfluorene)](PFNBr) and/or tris(phenylquinoxaline) (TPQ).

The EIL 380 is disposed between the second electrode 320 and the ETL370, and can improve physical properties of the second electrode 320 andtherefore, can enhance the life span of the OLED 300. In one exemplaryembodiment, the EIL 380 may include, but is not limited to, an alkalihalide such as LiF, CsF, NaF, BaF₂ and the like, and/or an organic metalcompound such as lithium benzoate, sodium stearate, and the like.

As an example, each of the ETL 370 and the EIL 380 may be laminated witha thickness of, but is not limited to, about 10 nm to about 100 nm.

When holes are transferred to the second electrode 320 via the EML 360and/or electrons are transferred to the first electrode 310 via the EML360, the luminous lifetime and the luminous efficiency of the OLED 300may be reduced. In order to prevent those phenomena, the OLED 300 inaccordance with this embodiment of the present disclosure has at leastone exciton blocking layer disposed adjacently to the EML 360.

For example, the OLED 300 of the exemplary embodiment includes the EBL355 between the HTL 350 and the EML 360 so as to control and preventelectron transfers. In one exemplary embodiment, the EBL 355 mayinclude, but is not limited to, TCTA, Tris[4-(diethylamino)phenyl]amine,N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine,TAPC, MTDATA, 1,3-bis(carbazol-9-yl)benzene (mCP),3,3′-bis(N-carbazolyl)-1,1′-biphenyl (mCBP), CuPc,N,N′-bis[4-(bis(3-methylphenyl)amino)phenyl]-N,N′-diphenyl[1,1′-biphenyl]-4,4′-diamine(DNTPD), TDAPB, 2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene,and/or 3,6-bis(N-carbazolyl)-N-phenyl-carbazole.

In addition, the OLED 300 further includes the HBL 375 as a secondexciton blocking layer between the EML 360 and the ETL 370 so that holescannot be transferred from the EML 360 to the ETL 370. In one exemplaryembodiment, the HBL 375 may include, but is not limited to,oxadiazole-based compounds, triazole-based compounds,phenanthroline-based compounds, benzoxazole-based compounds,benzothiazole-based compounds, benzimidazole-based compounds, andtriazine-based compounds.

For example, the HBL 375 may include a compound having a relatively lowHOMO energy level compared to the emitting material in EML 360. The HBL375 may include, but is not limited to, BCP, BAlq, Alq₃, PBD, spiro-PBD,Liq, Bis-4,5-(3,5-di-3-pyridylphenyl)-2-methylpyrimidine (B3 PYMPM),Oxybis(2,1-phenylene))bis(diphenylphosphine oxide (DPEPO),9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9′-bicarbazole andcombination thereof.

As described schematically above, the EML 360 of the OLED 300 inaccordance with the first embodiment of the present disclosure include ahost, and a dopant having a delayed fluorescent property (T dopant),which is the organic compound having the structure of any one inChemical Formulae 1, 4, 7, 8 and 11. When the EML 360 includes thedopant having the delayed fluorescent property, the OLED 300 improvesits luminous efficiency and its luminous lifetime and has a lowerdriving voltage.

An Organic Light Emitting Diode (OLED) emits light as holes injectedfrom the anode and electrons injected from the cathode are combined toform excitons in EML, and then unstable excited state excitons return toa stable ground state. Theoretically, when electrons meet holes to formexciton, a singlet exciton of a paired spin and a triplet exciton of anunpaired spin are produced by a ratio of 1:3 by spin arrangements. Onlythe singlet exciton among the excitons can be involved in emissionprocess in case of fluorescent materials. Accordingly, the OLED mayexhibit luminous efficiency by maximum 5% in case of using the commonfluorescent material.

In contrast, phosphorescent materials use different luminous mechanismof converting both singlet excitons and triplet exciton into light. Thephosphorescent materials can convert singlet excitons into tripletexcitons through intersystem crossing (ISC). Therefore, it is possibleto enhance luminous efficiency in case of applying the phosphorescentmaterials that use both the singlet excitons and the triplet excitonsduring the luminous process compared to the fluorescent materials.However, prior art blue phosphorescent materials exhibits too low of acolor purity to use with the display device and exhibits a very shortluminous lifetime, and therefore, they have not been used in commercialdisplay devices.

A delayed fluorescent material, which can solve the limitationsaccompanied by the prior art fluorescent dopants and the phosphorescentdopants, has been developed recently. Representative delayed fluorescentmaterial is a thermally-activated delayed fluorescent (TADF) material.Since the delayed fluorescent material generally has both an electrondonor moiety and an electron acceptor moiety within its molecularstructure, its triplet exciton energy can be converted upwardly to anintramolecular charge transfer (ICT) state. In case of using the delayedfluorescent material as a dopant, it is possible to use both theexcitons of singlet energy level S₁ and the excitons of triplet energylevel T₁ during the emission process.

The luminous mechanism of the delayed fluorescent material will beexplained with referring to FIG. 3, which is a schematic diagramillustrating a luminous mechanism of the delayed fluorescent material inan EML in accordance with another exemplary embodiment of the presentdisclosure. As illustrated in FIG. 3, both the excitons of singletenergy level S₁ ^(TD) and the excitons of triplet energy level T₁ ^(TD)in the delayed fluorescent material can move to an intermediate energylevel state, i.e. ICT state, and then the intermediate stated excitonscan be transferred to a ground state (S₀; S1→ICT←T₁). Since the excitonsof singlet energy level S₁ ^(TD) as well as the excitons of tripletenergy level T₁ ^(TD) in the delayed fluorescent material are involvedin the emission process, the delayed fluorescent material has improvedluminous efficiency.

Because both the HOMO and the LUMO are widely distributed over the wholemolecule within the common fluorescent material, it is not possible tointer-convert between the singlet energy level and the triplet energylevel within it (selection rule). In contrast, since the delayedfluorescent material, which can be converted to ICT state, has littleorbital overlaps between HOMO and LUMO, there is little interactionbetween the HOMO state molecular orbital and the LUMO state molecularorbital in the state where dipole moment is polarized within the delayedfluorescent material. As a result, the changes of spin states ofelectrons does not have an influence on other electrons, and a newcharge transfer band (CT band) that does not follow the selection ruleis formed in the delayed fluorescent material.

In other words, since the delayed fluorescent material has the electronacceptor moiety spacing apart from the electron donor moiety within themolecule, it exists as a polarized state having a large dipole momentwithin the molecule. As the interaction between HOMO molecular orbitaland LUMO molecular orbital becomes little in the state where the dipolemoment is polarized, both the triplet energy level excitons and thesinglet energy level excitons can be converted to ICT state.Accordingly, the excitons of triplet energy level T₁ as well as theexcitons of singlet energy level S₁ can be involved in the emissionprocess.

In case of driving the diode that includes the delayed fluorescentmaterial, 25% excitons of singlet energy level S₁ ^(TD) and 75% excitonsof triplet energy level T₁ ^(TD) are converted to ICT state by heat orelectrical field, and then the converted excitons transfer to the groundstate S₀ with luminescence. Therefore, the delayed fluorescent materialmay have 100% internal quantum efficiency in theory.

The delayed fluorescent material must have an energy level bandgapΔE_(ST) ^(TD) equal to or less than about 0.3 eV, for example, fromabout 0.05 to about 0.3 eV, between the singlet energy level S₁ ^(TD)and the triplet energy level T₁ ^(TD) so that exciton energy in both thesinglet energy level and the triplet energy level can be transferred tothe ICT state. The material having little energy level bandgap betweenthe singlet energy level S₁ ^(TD) and the triplet energy level T₁ ^(TD)can exhibit common fluorescence in which the excitons of singlet energylevel S₁ ^(TD) can be transferred to the ground state S₀, as well asdelayed fluorescence with Reverse Inter System Crossing (RISC) in whichthe excitons of triplet energy level T₁ ^(TD) can be transferredupwardly to the excitons of singlet energy level S₁ ^(TD), and then theexciton of singlet energy level S₁ ^(TD) transferred from the tripletenergy level T₁ ^(TD) can be transferred to the ground state S₀.

The delayed fluorescent material can realize identical quantumefficiency as the prior art phosphorescent material including heavymetals because the delayed fluorescent material can obtain a theoreticalluminous efficiency up to 100%. The host for implementing the delayedfluorescence can induce triplet exciton energy generated at the delayedfluorescent material to be involved in the luminous process withoutquenching as a non-emission. In order to induce such exciton energytransfer, energy levels among the host and the delayed fluorescentmaterial should be adjusted.

FIG. 4 is a schematic diagram illustrating a luminous mechanism byenergy level bandgaps between luminous materials in accordance with anexemplary embodiment of the present disclosure. As illustratedschematically in FIG. 4, each of an excited state singlet energy levelS₁ ^(H) and an excited state triplet energy level T₁ ^(H) of the hostshould be higher than each of an excited state singlet energy level S₁^(TD) and an excited state triple energy level T₁ ^(TD) of the dopant,which has the delayed fluorescent property and is the organic compoundhaving the structure of any one in Chemical Formulae 1, 4, 7, 8 and 11,respectively. For example, the excited triplet energy level T₁ ^(H) ofthe host may be higher than the excited state triplet energy level T₁^(TD) of the dopant by at least about 0.2 eV.

As an example, when the excited state triplet energy level T₁ ^(H) ofthe host is not sufficiently higher than the excited state tripletenergy levels of the dopant, which may be a delayed fluorescentmaterial, the excitons of the triplet state level T₁ ^(H) of the dopantcan be reversely transferred to the excited state triplet energy levelT₁ ^(H) of the host, which cannot utilize triplet exciton energy.Accordingly, the excitons of the triplet state level T₁ ^(TD) of thedopant having the delayed fluorescent property may be quenched as anon-emission and the triplet state excitons of the dopant cannot beinvolved in the emission. As an example, the host may have an excitedstate singlet energy level S₁ ^(H) of equal to or more than about 2.8 eVand an excited state triplet energy level T₁ ^(H) of equal to or morethan about 2.6 eV, but are not limited thereto.

The dopant (TD), which has the delayed fluorescent material, which maybe the organic compound having the structure of any one in ChemicalFormulae 1, 4, 7, 8 and 11, should have an energy level bandgap ΔE_(ST)^(TD) between the excited stated singlet energy level S₁ ^(TD) and theexcited state triplet energy level T₁ ^(TD) equal to or less than about0.3 eV, for example between about 0.05 and about 0.3 eV, in order torealize delayed fluorescence (See, FIG. 3).

In addition, it is necessary to adjust properly HOMO energy levels andLUMO energy levels of the host and the dopant, which may be thefluorescent material. For example, it is preferable that an energy levelbandgap (|HOMO^(H)-HOMO^(TD)|) between a HOMO energy level (HOMO^(H)) ofthe host and a HOMO energy level (HOMO^(TD)) of the dopant, or an energylevel bandgap (|LUMO^(H)-LUMO^(TD)|) between a LUMO energy level(LUMO^(H)) of the host and a LUMO energy level (LUMO^(TD)) of the dopantmay be equal to or less than about 0.5 eV, for example, between about0.1 eV to about 0.5 eV. In this case, the charges can be transportedefficiently from the host to the first dopant and thereby enhancing anultimate luminous efficiency.

Moreover, an energy level bandgap (Eg^(H)) between the HOMO energy level(HOMO^(H)) and the LUMO energy level (LUMO^(H)) of the host may belarger than an energy level bandgap (Eg^(TD)) between the HOMO energylevel (HOMO^(TD)) and the LUMO energy level (LUMO^(TD)) of the dopant.As an example, the HOMO energy level (HOMO^(H)) of the host is deeper orlower than the HOMO energy level (HOMO^(TD)) of the dopant, and the LUMOenergy level (LUMO^(H)) of the host is shallower or higher than the LUMOenergy level (LUMO^(TD)) of the dopant.

In one exemplary embodiment, the organic compound having the structureof any one in Chemical Formulae 1, 4, 7, 8 and 11, as the dopant havingthe delayed fluorescent dopant, may have a HOMO energy level (HOMO^(TD))between about −5.0 and about −6.0 eV, and preferably between about −5.0and about −5.5 eV and a LUMO energy level (LUMO^(TD)) between about −2.5and about −3.5 eV, and preferably about −2.5 and about −3.0 eV. Also, anenergy level bandgap (Eg^(TD)) between those HOMO and LUMO energy levelsof the organic compound may be between about 2.2 to about 3.0 eV, andpreferably about 2.4 and about 2.8 eV. In addition, the host may have aHOMO energy level (HOMO′) between about −5.0 and about −6.5 eV, andpreferably between about −5.5 and about −6.2 eV and a LUMO energy level(LUMO^(TD)) between about −1.5 and about −3.0 eV, and preferably about−1.5 and about −2.0 eV. Also, an energy level bandgap (Eg^(H)) betweenthose HOMO and LUMO energy levels of the host may be between about 3.0to about 4.0 eV, and preferably about 3.0 and about 3.5 eV.

In one exemplary embodiment, the host in the EML 360 may include, but isnot limited to,9-(3-(9H-carbazol-9-yl)phenyl)-9H-carbazole-3-carbonitrile (mCP-CN),CBP, mCBP, mCP, DPEPO, 2,8-bis(diphenylphosphoryl)dibenzothiophene(PPT), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB),2,6-di(9H-carbazol-9-yl)pyridine (PYD-2Cz),2,8-di(9H-carbazol-9-yl)dibenzothiophene (DCzDBT),3′,5′-Di(carbazol-9-yl)-[1,1′-bipheyl]-3,5-dicarbonitrile (DCzTPA),4-(9H-carbazol-9-yl)biphenyl-3,5-dicarbonitrile (pCzB-2CN),3′-(9H-carbazol-9-yl)biphenyl-3,5-dicarbonitrile (mCzB-2CN),diphenyl-4-triphenylsilylphenyl-phosphine oxide (TSPO1),9-(9-phenyl-9H-carbazol-6-yl)-9H-carbazole (CCP),9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9′-bicarbazole and/or4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.

When the EML 360 includes the host and the dopant, i.e. the organiccompound having the structure of any one in Chemical Formulae 1, 4, 7, 8and 11, the weight ratio of the host may be equal to or more than theweight ratio of the dopant. As an example, the EML 360 may include thedopant of about 1 to about 50% by weight, preferably of about 10 toabout 40% by weight, and more preferably of about 20 to about 40% byweight. The EML 360 may be laminated with a thickness of, but is notlimited to, about 10 nm to about 200 nm, preferably about 20 nm to about100 nm, and more preferably about 30 nm to about 50 nm.

In the above first embodiment, the EML 360 includes only one dopanthaving the delayed fluorescent property. Unlike that embodiment, the EMLmay include plural dopants having different luminous properties. FIG. 5is a schematic cross-sectional view illustrating an organic lightemitting diode in accordance with another exemplary embodiment of thepresent disclosure. As illustrated in FIG. 5, the OLED 300A according tothe second embodiment of the present disclosure includes first andsecond electrodes 310 and 320 facing each other and an emitting unit 330a disposed between the first and second electrodes 310 and 320.

In one exemplary embodiment, the emitting unit 330 a as an emissionlayer includes a HIL 340, a HTL 350, an EML 360 a, an ETL 370 and an EIL380 each of which is laminated sequentially over the first electrode310. Alternatively, the emitting unit 330 a may further include a firstexciton blocking layer, i.e. an EBL 355 disposed between the HTL 350 andthe EML 360 a and/or a second exciton blocking layer, i.e. a HBL 375disposed between the EML 360 a and the ETL 370. The emitting unit 330 amay have the same configurations and materials as the emitting unit 330in FIG. 2 except the EML 360 a.

The EML 360 a may include a host (a first host), a first dopant and asecond dopant. The first dopant may be a delayed fluorescent dopant (Tdopant; TD) and the second dopant may be a fluorescent dopant (F dopant;FD). In this case, the organic compound having the structure of any onein Chemical Formulae 1, 4, 7, 8 and 11 may be used as the first dopantand a fluorescent or phosphorescent material may be sued as the seconddopant. The OLED 300A can implement hyper-fluorescence enhancing itsluminous efficiency by adjusting energy levels among the luminousmaterials, i.e. the host and the dopants.

FIG. 6 is a schematic diagram illustrating luminous mechanism by energylevel bandgap among luminous materials in accordance with anotherexemplary embodiment of the present disclosure.

When an EML includes only the dopant which has the delayed fluorescentproperty and has the structure of any one in Chemical Formula 1, 4, 7, 8and 11, the EML may implement high internal quantum efficiency as theprior art phosphorescent materials including heavy metals because thedopant can exhibit 100% internal quantum efficiency in theory.

However, because of the bond formation between the electron acceptor andthe electron donor and conformational twists within the delayedfluorescent material, additional charge transfer transition (CTtransition) within the delayed fluorescent material is caused thereby,and the delayed fluorescent material have various geometry. As a result,the delayed fluorescent materials show emission spectra having verybroad FWHM (full-width at half maximum) in the course of emission, whichresults in poor color purity. In addition, the delayed fluorescentmaterial utilizes the triplet exciton energy as well as the singletexciton energy in the luminous process with rotating each moiety withinits molecular structure, which results in twisted internal chargetransfer (TICT). As a result, the luminous lifetime of an OLED includingonly the delayed fluorescent materials may be reduced owing to weakeningof molecular bonding forces among the delayed fluorescent materials.

In the second embodiment, the EML 360 a further includes the seconddopant, which may be a fluorescent or phosphorescent material, in orderto prevent the color purity and luminous lifetime from being reduced incase of using only the delayed fluorescent materials. The tripletexciton energy of the first dopant (T dopant), which may be the delayedfluorescent material, is converted upwardly to the singlet excitonenergy of its own by RISC mechanism, then the converted singlet excitonenergy of the first dopant can be transferred to the second dopant (Fdopant), which may be the fluorescent or phosphorescent material, in thesame EML 360 a by Dexter energy transfer mechanism, which transferexciton energies depending upon wave function overlaps among adjacentmolecules by inter-molecular electron exchanges and exciton diffusions.

When the EML 360 a includes the host, the first dopant (T dopant) whichmay be the organic compound having the structure of any one in ChemicalFormulae 1, 4, 7, 8 and 11 and having the delayed fluorescent propertyand the second dopant (F dopant) which may be the fluorescent orphosphorescent material, it is necessary to adjust properly energylevels amount those luminous materials.

An energy level bandgap between an excited state singlet energy level S₁^(TD) and an excited state triplet energy level T₁ ^(TD) of the firstdopant (T dopant), which is the organic compound having the structure ofany one in Chemical Formulae 1, 4, 7, 8 and 11, may be equal to or lessthan about 0.3 eV in order to realize the delayed fluorescence. Inaddition, each of an excited state singlet energy level S₁ ^(H) and anexcited state triplet energy level T₁ ^(H) of the host is higher thaneach of the excited state singlet energy level S₁ ^(TD) and the excitedstate triplet energy level T₁ ^(TD) of the first dopant, respectively.As an example, the excited state triplet energy level T₁ ^(H) of thehost may be higher than the excited state triplet energy level T₁ ^(TD)of the first dopant by at least about 0.2 eV. Moreover, the excitedstate triplet energy level T₁ ^(TD) of the first dopant is higher thanan excited state triplet energy level T₁ ^(FD) of the second dopant. Inone exemplary embodiment, the excited state singlet energy level S₁^(TD) of the first dopant may be higher than an excited state singletenergy level S₁ ^(FD) of the second dopant as a fluorescent material.

In addition, an energy level bandgap (|HOMO^(H)-HOMO^(TD)|) between aHOMO energy level (HOMO^(H)) of the host and a HOMO energy level(HOMO^(TD)) of the first dopant, or an energy level bandgap(|LUMO^(H)-LUMO^(TD)|) between a LUMO energy level (LUMO^(H)) of thehost and a LUMO energy level (LUMO^(TD)) of the first dopant may beequal to or less than about 0.5 eV.

For example, the host may include, but is not limited to, mCP-CN, CBP,mCBP, mCP, DPEPO, PPT, TmPyPB. PYD-2Cz, DCzDBT, DCzTPA, pCzB-2CN,mCzB-2CN, TSPO1, CCP,9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9′-bicabazole and/or4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.

The exciton energy should be effectively transferred from the firstdopant as the delayed fluorescent material to the second dopant as thefluorescent or phosphorescent material in order to implementhyper-fluorescence. With regard to energy transfer efficiency from thedelayed fluorescent material to the fluorescent or phosphorescentmaterial, an overlap between an emission spectrum of the delayedfluorescent material and an absorption spectrum of the fluorescent orphosphorescent material can be considered. As an example, a fluorescentor phosphorescent material having an absorption spectrum withoverlapping area with an emission spectrum of the first dopant, i.e. theorganic compound having the structure of any one in Chemical Formulae 1,4, 7, 8 and 11, may be used as the second dopant in order to transferexciton energy efficiently from the first dopant to the second dopant.

In one exemplary embodiment, the fluorescent material as the seconddopant may have, but is not limited to, quinolino-acridine core. As anexample, the second dopant having the quinolino-acridine core mayinclude 5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione(S₁:2.3 eV; T₁: 2.0 eV; LUMO: −3.0 eV; HOMO: −5.4 eV),5,12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione(S₁: 2.3 eV; T₁:2.2 eV; LUMO: −3.0 eV; HOMO: −5.4 eV),5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,12H)-dione(S₁: 2.2 eV; T₁: 2.0 eV; LUMO: −3.1 eV; HOMO: −5.5 eV),5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,12H)-dione(S₁: 2.2 eV; T₁: 2.0 eV; LUMO: −3.1 eV; HOMO: −5.5 eV),5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,12H)-dione(S: 2.0 eV; T₁: 1.8 eV; LUMO: −3.3 eV; HOMO: −5.5 eV).

In addition, the fluorescent material as the second dopant may include,but is not limited to,1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(DCJTB;S₁: 2.3 eV; T₁: 1.9 eV; LUMO: −3.1 eV; HOMO: −5.3 eV). Moreover, metalcomplexes which can emit light of green color may be used as the seconddopant.

In one exemplary embodiment, the weight ratio of the host may be largerthan the weight ratio of the first and second dopants in the EML 360 a,and the weight ratio of the first dopant may be larger larger than theweight ratio of the second dopant. In an alternative embodiment, theweight ratio of the host is larger than the weight ratio of the firstdopant and the weight ratio of the first dopant is larger than theweight ratio of the second dopant. When the weight ratio of the firstdopant is larger than the weight ratio of the second dopant, excitionenergy can be transferred enough from the first dopant to the seconddopant by Dexter energy transfer mechanism. As an example, the EML 360 aincludes the host of about 60 to about 75% by weight, the first dopantof about 20 to about 40% by weight and the second dopant of about 0.1 toabout 5% by weight.

The OLEDs in accordance with the previous embodiments have asingle-layered EML. Alternatively, an OLED in accordance with thepresent disclosure may include multiple-layered EML. FIG. 7 is aschematic cross-sectional view illustrating an organic light emittingdiode having a double-layered EML in accordance with another exemplaryembodiment of the present disclosure. FIG. 8 is a schematic diagramillustrating luminous mechanism by energy level bandgap among luminousmaterials in accordance with another exemplary embodiment of the presentdisclosure.

As illustrated in FIG. 7, the OLED 400 in accordance with an exemplarythird embodiment of the present disclosure includes first and secondelectrodes 410 and 420 facing each other and an emitting unit 430 as anemission layer disposed between the first and second electrodes 410 and420.

In one exemplary embodiment, the emitting unit 430 includes an HIL 440,an HTL 450, and EML 460, an ETL 470 and an EIL 480 each of which islaminated sequentially over the first electrode 410. In addition, theemitting unit 430 may further include an EBL 455 as a first excitonblocking layer disposed between the HTL 450 and the EML 460, and/or anHBL 475 as a second exciton blocking layer disposed between the EML 460and the ETL 470.

As described above, the first electrode 410 may be an anode and mayinclude, but is not limited to, a conductive material having arelatively large work function values such as ITO, IZO, SnO, ZnO, ICO,AZO, and the like. The second electrode 420 may be a cathode and mayinclude, but is not limited to, a conductive material having arelatively small work function values such as Al, Mg, Ca, Ag, alloythereof or combination thereof.

The HIL 440 is disposed between the first electrode 410 and the HTL 450.The HIL 440 may include, but is not limited to, MTDATA. NATA, 1T-NATA,2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN, TDAPB, PEDOT/PSS and/orN-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine.The HIL 440 may be omitted in compliance with the structure of the OLED400.

The HTL 450 is disposed adjacently to the EML 460 between the firstelectrode 410 and the EML 460. The HTL 450 may include, but is notlimited to, aromatic amine compounds such as TPD, NPD(NPB), CBP,poly-TPD, TFB, TAPC,N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amineand/orN-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine.

The EML 460 includes a first EML (EML1) 462 and a second EML (EML2) 464.The EML1 462 is disposed between the EBL 455 and the HBL 475 and theEML2 464 is disposed between the EML1 462 and the HBL 475. One of theEML1 462 and the EML2 464 includes a first dopant (T dopant) having adelayed fluorescent property, for example, an organic compound havingthe structure of any one in Chemical Formulae 1, 4, 7, 8 and 11, theother of the EML 1462 and the EML2 464 includes a second dopant (Fdopant) as a fluorescent or phosphorescent material. The configurationand energy levels among the luminous materials in the EML 460 will beexplained in more detail below.

The ETL 470 is disposed between the EML 460 and the EIL 480. In oneexemplary embodiment, the ETL 470 may include, but is not limited to,oxadiazole-based compounds, triazole-based compounds,phenanthroline-based compounds, benzoxazole-based compounds,benzothiazole-based compounds, benzimidazole-based compounds,triazine-based compounds, and the like. As an example, the ETL 470 mayinclude, but is not limited to, Alq₃, PBD, spiro-PBD, Liq, TPBi, BAlq,Bphen, NBphen, BCP, TAZ, NTAZ, TpPyPB, TmPPPyTz, PFNBr and/or TPQ.

The EIL 480 is disposed between the second electrode 420 and the ETL470. In one exemplary embodiment, the EIL 480 may include, but is notlimited to, an alkali halide such as LiF, CsF, NaF, BaF₂, and the like,and/or an organic metal compound such as lithium benzoate, sodiumstearate, and the like.

The EBL 455 is disposed between the HTL 450 and the EML 460 forcontrolling and preventing electron transportations between the HTL 450and the EML 460. As an example, The EBL 455 may include, but is notlimited to, TCTA, Tris[4-(diethylamino)phenyl]amine,N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine,TAPC, MTDATA, mCP, mCBP, CuPc, DNTPD, TDAPB,2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or3,6-bis(N-carbazolyl)-N-phenyl-carbazole.

The HBL 475 is disposed between the EML 460 and the ETL 470 forpreventing hole transportations between the EML 460 and the ETL 470. Inone exemplary embodiment, the HBL 475 may include, but is not limitedto, oxadiazole-based compounds, triazole-based compounds,phenanthroline-based compounds, benzoxazole-based compounds,benzothiazole-based compounds, benzimidazole-based compounds, andtriazine-based compounds. As an example, the HBL 475 may include acompound having a relatively low HOMO energy level compared to theemitting material in EML 460. The HBL 475 may include, but is notlimited to, BCP, BAlq, Alq₃, PBD, spino-PBD, Liq, B3PYMPM, DPEPO,9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9′-bicarbazole andcombination thereof.

In the exemplary third embodiment, the EML1 462 includes a first hostand a first dopant, which is a delayed fluorescent material and the EML464 includes a second host and a second dopant, which is a fluorescentor phosphorescent material.

The EML1 462 includes the first host and the first dopant which is thedelayed fluorescent material, i.e. the organic compound having thestructure of any one in Chemical Formulae 1, 4, 7, 8 and 11. An energylevel bandgap (ΔE_(ST) ^(TD)) between the excited state singlet energylevel S₁ ^(TD) and the excited state triplet energy level T₁ ^(TD) ofthe first dopant is very small (ΔE_(ST) ^(TD) is equal to or less thanabout 0.3 eV; See, FIG. 3) so that triplet exciton energy of the firstdopant can be transferred to the singlet exciton energy of its own byRISC mechanism. While the first dopant has high internal quantumefficiency, but it has poor color purity due to its wide FWHM(full-width half maximum).

On the contrary, the EML2 464 may include the second host and the seconddopant as a fluorescent material. While the second dopant as afluorescent material has advantage in terms of color purity due to itsnarrow FWHM, but its internal quantum efficiency is low because itstriplet exciton cannot be involved in a luminous process.

However, in this exemplary embodiment, the singlet exciton energy andthe triplet exciton energy of the first dopant, which has the delayedfluorescent property, in the EML 1 462 can be transferred to the seconddopant, which may be the fluorescent or phosphorescent material, in theEML2 464 disposed adjacently to the EML1 462 by FRET (Forster resonanceenergy transfer) mechanism, which transfers energy non-radially throughelectrical fields by dipole-dipole interactions. Accordingly, theultimate emission occurs in the second dopant within the EML2 464.

In other words, the triplet exciton energy of the first dopant isconverted upwardly to the singlet exciton energy of its own in the EML1462 by RISC mechanism. Then, the converted singlet exciton energy of thefirst dopant is transferred to the singlet exciton energy of the seconddopant because the excited state singlet energy level S₁ ^(TD) of thefirst dopant is higher than the excited state singlet energy level S₁^(TD) of the second dopant (See, FIG. 8). The second dopant in the EML2464 can emit light using the triplet exciton energy as well as thesinglet exciton energy.

As the exciton energy, which is generated at the first dopant as thedelayed fluorescent material in the EML1 462, is efficiently transferredfrom the first dopant to the second dopant in the EML2 464, ahyper-fluorescence can be realized. In this case, the first dopant onlyacts as transferring exciton energy to the second dopant. Substantiallight emission is occurred in the EML2 464 including the second dopantwhich is the fluorescent or phosphorescent dopant and has a narrow FWHM.Accordingly, the OLED 400 can enhance its quantum efficiency and improveits color purity due to narrow FWHM.

Each of the EML1 462 and the EML2 464 includes the first host and thesecond host, respectively. The exciton energies generated at the firstand second hosts should be transferred to the first dopant as thedelayed fluorescent material to emit light. It is necessary to adjustenergy levels among the luminous materials in order to realize ahyper-fluorescence.

As illustrated in FIG. 8, each of excited state singlet energy levels S₁^(H1) and S₁ ^(H2) and excited state triplet energy levels T₁ ^(H1) andT₁ ^(H2) of the first and second hosts should be higher than each of theexcited state singlet energy level S₁ ^(TD) and the excited statetriplet energy level T₁ ^(TD) of the first dopant as the delayedfluorescent material, respectively.

For example, when each of the excited triplet energy levels T₁ ^(H1) andT₁ ^(H2) of the first and second hosts is not high enough than theexcited state triplet energy level T₁ ^(TD) of the first dopant, thetriplet exciton of the first dopant may be reversely transferred to theexcited state triplet energy levels T₁ ^(H1) and T₁ ^(H2) of the firstand second hosts, which cannot utilize triplet exciton energy.Accordingly, the excitons of the triplet state level T₁ ^(TD) of thefirst dopant may be quenched as a non-emission and the triplet stateexcitons of the first dopant cannot be involved in the emission. As anexample, each of the excited state triplet energy levels T₁ ^(H1) and T₁^(H2) of the first and second hosts may be higher than the excited statetriplet energy level T₁ ^(TD) of the first dopant by at least about 0.2eV.

The excited state singlet energy level S₁ ^(H2) of the second host ishigher than an excited state singlet energy level S₁ ^(FD) of the seconddopant. In this case, the singlet exciton energy generated at the secondhost can be transferred to the excited singlet energy level S₁ ^(FD) ofthe second dopant.

In addition, it is necessary for the EML 460 to implement high luminousefficiency and color purity as well as to transfer exciton energyefficiently from the first dopant, which is converted to ICT complexstate by RISC mechanism in the EML1 462, to the second dopant which isthe fluorescent or phosphorescent material in the EML2 464. In order torealize such an OLED 400, the excited state triplet energy level T₁^(TD) of the first dopant is higher than an excited state triplet energylevel T₁ ^(FD) of the second dopant. In one exemplary embodiment, theexcited state singlet energy level S₁ ^(TD) of the first dopant ishigher than an excited state singlet energy level S₁ ^(FD) of the seconddopant as a fluorescent material.

In one exemplary embodiment, the energy level bandgap between theexcited state singlet energy level S₁ ^(TD) and the excited statetriplet energy level T₁ ^(TD) of the first dopant may be equal to orless than about 0.3 eV. In addition, an energy level bandgap(|HOMO^(H)-HOMO^(TD)|) between a HOMO energy level (HOMO^(H)) of thefirst and/or second hosts and a HOMO energy level (HOMO^(TD)) of thefirst dopant, or an energy level bandgap (|LUMO^(H)-LUMO^(TD)|) betweena LUMO energy level (LUMO^(H)) of the first and/or second hosts and aLUMO energy level (LUMO^(TD)) of the first dopant may be equal to orless than about 0.5 eV.

When the luminous materials do not satisfy the required energy levels asdescribed above, exciton energies are quenched at the first and seconddopants or exciton energies cannot transferred efficiently from the hostto the dopants, so that OLED 400 may have reduced quantum efficiency.

The first host and the second host may be the same or different fromeach other. For example, each of the first host and the second host mayindependently include, but is not limited to, mCP-CN, CBP, mCBP, mCP,DPEPO, PPT, TmPyPB, PYD-2Cz. DCzDBT, DCzTPA, pCzB-2CN, mCzB-2CN, TSPO1,CCP, 9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9′-bicarbazole and/or4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.

The second dopant may have narrow FWHM and have luminous spectrum havinglarge overlapping area with the absorption spectrum of the first dopant.As an example, the second dopant may include, but is not limited to, anorganic compound having a quinolino-acridine core such as5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,12H)-dione,5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-]acridine-7,14(5H,12H)-dione, DCJTB and any metal complexes which can emit light of greencolor.

In one exemplary embodiment, each of the first and second hosts in theEML1 462 or the EML2 464 may have weight ratio equal to or more than thefirst dopant and the second dopant in the same EMLs 462 and 464,respectively. In addition, the weight ratio of the first dopant in theEML1 462 may be larger than the weight ratio of the second dopant in theEML2 464. In this case, it is possible to transfer enough exciton energyfrom the first dopant in the EML1 462 to the second dopant in the EML2464.

Particularly, the weight ratio of the first host may be equal to or morethan the weight ratio of the first dopant in the EML1 462. As anexample, the EML1 462 may include the first host of about 50 to about90% by weight, preferably about 60 to about 90% by weight, and morepreferably about 60 to about 80% by weight, and the first dopant ofabout 1 to about 50% by weight, preferably about 10 to about 40% byweight, and more preferably about 20 to about 40% by weight.

The weight ratio of the second host may be more than the weight ratio ofthe second dopant in the EML2 464. As an example, the EML2 464 mayinclude the second host of about 90 to about 99% by weight, andpreferably about 95 to about 99% by weight and the second dopant ofabout 1 to about 10% by weight, and preferably about 1 to about 5% byweight.

Each of the EML1 462 and the EML2 464 may be laminated with a thicknessof, but is not limited to, about 5 to about 100 nm, preferably about 10nm to about 30 nm, and more preferably about 10 nm to about 20 nm.

When the EML2 464 is disposed adjacently to the HBL 475 in one exemplaryembodiment, the second host, which is included in the EML2 464 togetherwith the second dopant, may be the same material as the HBL 475. In thiscase, the EML2 464 may have a hole blocking function as well as anemission function. In other words, the EML2 464 can act as a bufferlayer for blocking holes. In one embodiment, the HBL 475 may be omittedwhere the EML2 464 may be a hole blocking layer as well as an emittingmaterial layer.

When the EML2 464 is disposed adjacently to the EBL 455 in anotherexemplary embodiment, the second host may be the same material as theEBL 455. In this case, the EML2 464 may have an electron blockingfunction as well as an emission function. In other words, the EML2 464can act as a buffer layer for blocking electrons. In one embodiment, theEBL 455 may be omitted where the EML2 464 may be an electron blockinglayer as well as an emitting material layer.

An OLED having a triple-layered EML will be explained. FIG. 9 is aschematic cross-sectional view illustrating an organic light emittingdiode having a triple-layered EML in accordance with another exemplaryembodiment of the present disclosure. FIG. 10 is a schematic diagramillustrating luminous mechanism by energy level bandgap among luminousmaterials in accordance with another exemplary embodiment of the presentdisclosure.

As illustrated in FIG. 9, an OLED 500 in accordance with the fourthembodiment of the present disclosure includes first and secondelectrodes 510 and 520 facing each other and an emitting unit 530 as anemission layer disposed between the first and second electrodes 510 and520.

In one exemplary embodiment, the emitting unit 530 includes an HIL 540,an HTL 550, and EML 560, an ETL 570 and an EIL 580 each of which islaminated sequentially over the first electrode 510. In addition, theemitting unit 530 may further include an EBL 555 as a first excitonblocking layer disposed between the HTL 550 and the EML 560, and/or anHBL 575 as a second exciton blocking layer disposed between the EML 560and the ETL 570.

As described above, the first electrode 510 may be an anode and mayinclude, but is not limited to, a conductive material having arelatively large work function values such as ITO, IZO, SnO, ZnO, ICO,AZO, and the like. The second electrode 520 may be a cathode and mayinclude, but is not limited to, a conductive material having arelatively small work function values such as Al, Mg, Ca, Ag, alloythereof or combination thereof.

The HIL 540 is disposed between the first electrode 510 and the HTL 550.The HIL 540 may include, but is not limited to, MTDATA, NATA, 1T-NATA,2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN, TDAPB, PEDOT/PSS and/orN-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine.The HIL 540 may be omitted in compliance with the structure of the OLED500.

The HTL 550 is disposed adjacently to the EML 560 between the firstelectrode 510 and the EML 560. The HTL 550 may include, but is notlimited to, aromatic amine compounds such as TPD, NPD(NPB), CBP,poly-TPD, TFB, TAPC,N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amineand/orN-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine.

The EML 560 includes a first EML (EML1) 562, a second EML (EML2) 564 anda third EML (EML3) 566. The EML1 562 is disposed between the EBL 555 andthe HBL 575, the EML2 564 is disposed between the EBL 555 and the EML1562 and the EML3 566 is disposed between the EML1 562 and the HBL 575.The configuration and energy levels among the luminous materials in theEML 560 will be explained in more detail below.

The ETL 570 is disposed between the EML 560 and the EIL 580. In oneexemplary embodiment, the ETL 570 may include, but is not limited to,oxadiazole-based compounds, triazole-based compounds,phenanthroline-based compounds, benzoxazole-based compounds,benzothiazole-based compounds, benzimidazole-based compounds,triazine-based compounds, and the like. As an example, the ETL 570 mayinclude, but is not limited to, Alq₃, PBD, spiro-PBD, Liq, TPBi, BAlq,Bphen. NBphen. BCP, TAZ, NTAZ, TpPyPB, TmPPPyTz, PFNBr and/or TPQ.

The EIL 580 is disposed between the second electrode 520 and the ETL570. In one exemplary embodiment, the EIL 580 may include, but is notlimited to, an alkali halide such as LiF, CsF, NaF, BaF₂ and the like,and/or an organic metal compound such as lithium benzoate, sodiumstearate, and the like.

The EBL 555 may be disposed between the HTL 550 and the EML 560 forcontrolling and preventing electron transportations between the HTL 550and the EML 560. As an example, The EBL 555 may include, but is notlimited to, TCTA, Tris[4-(diethylamino)phenyl]amine,N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine,TAPC, MTDATA, mCP, mCBP, CuPe, DNTPD, TDAPB,2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or3,6-bis(N-carbazolyl)-N-phenyl-carbazole.

The HBL 575 may be disposed between the EML 560 and the ETL 570 forpreventing hole transportations between the EML 560 and the ETL 570. Inone exemplary embodiment, the HBL, 575 may include, but is not limitedto, oxadiazole-based compounds, triazole-based compounds,phenanthroline-based compounds, benzoxazole-based compounds,benzothiazole-based compounds, benzimidazole-based compounds, andtriazine-based compounds. As an example, the HBL 575 may include acompound having a relatively low HOMO energy level compared to theemitting material in EML 560. The HBL 575 may include, but is notlimited to, BCP, BAlq, Alq₃, PBD, spiro-PBD, Liq, B3PYMPM, DPEPO,9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9′-bicarbazole andcombination thereof.

The EML1 562 includes a first dopant (T dopant) having a delayedfluorescent property, i.e. the organic compound having the structure ofany one in Chemical Formulae 1, 4, 7, 8 and 11. Each of the EML2 564 andthe EML3 566 includes a second dopant (a first fluorescent orphosphorescent dopant, F dopant 2) and a third dopant (a secondfluorescent or phosphorescent dopant). Each of the EML1 562, EML2 564and EML3 566 further includes a first host, a second host and a thirdhost, respectively.

In accordance with this embodiment, the singlet energy as well as thetriplet energy of the first dopant (T dopant) as the delayed fluorescentmaterial, i.e. the organic compound having the structure of any one inChemical Formulae 1, 4, 7, 8 and 11 in the EML1 562 can be transferredto the second and third dopants (F dopants 1 and 2) each of which isincluded in the EML2 564 and EML3 566 disposed adjacently to the EML1562 by FRET energy transfer mechanism. Accordingly, the ultimateemission occurs in the second and third dopants in the EML2 564 and theEML3 566.

In other words, the triplet exciton energy of the first dopant isconverted upwardly to the singlet exciton energy of its own in the EML1562 by RISC mechanism, then the singlet exciton energy of the firstdopant is transferred to the singlet exciton energy of the second andthird dopants in the EML2 564 and the EML3 566 because the excited statesinglet energy level S₁ ^(TD) of the first dopant is higher than each ofthe excited state singlet energy levels S₁ ^(FD1) and S₁ ^(FD2) of thesecond and third dopants (See, FIG. 10). The singlet exciton energy ofthe first dopant in the EML1 562 is transferred to the second and thirddopants in the EML2 564 and the EML3 566 which are disposed adjacentlyto the EML1 562 by FRET mechanism.

The second and third dopants in the EML2 564 and EML3 566 can emit lightusing the singlet exciton energy and the triplet exciton energy derivedfrom the first dopant. Each of the second and third dopants may havenarrower FWHM compared to the first dopant. As the exciton energy, whichis generated at the first dopant as the delayed fluorescent material inthe EML1 562, is transferred to the second and third dopants in the EML2564 and the EML3 566, a hyper-fluorescence can be realized. In thiscase, the first dopant only acts as transferring energy to the secondand third dopants. The EML1 562 including the first dopant is notinvolved in the ultimate emission process. Substantial light emission isoccurred in the EML2 564 and in the EML3 566 each of which includes thesecond dopant and the third dopant with a narrow FWHM. Accordingly, theOLED 500 can enhance its quantum efficiency and improve its color puritydue to narrow FWHM. As an example, each of the second and third dopantsmay have an emission wavelength range having a large overlapping areawith an absorption wavelength range of the first dopant, so that excitonenergy of the first dopant may be transferred efficiently to each of thesecond and third dopants.

In this case, it is necessary to adjust properly energy levels among thehosts and the dopants in the EML1 562, the EML2 564 and the EML3 566. Asillustrated in FIG. 10, each of excited state singlet energy levels S₁^(H1), S₁ ^(H2) and S₁ ^(H3) and excited state triplet energy levels T₁^(H1), T₁ ^(H2) and T₁ ^(H3) of the first to third hosts should behigher than each of the excited state singlet energy level S₁ ^(TD) andthe excited state triplet energy level T₁ ^(TD) of the first dopant asthe delayed fluorescent material, respectively.

For example, when each of the excited triplet energy levels T₁ ^(H1), T₁^(H2) and T₁ ^(H3) of the first to third hosts is not high enough thanthe excited state triplet energy level T₁ ^(TD) of the first dopant, thetriplet exciton of the first dopant may be reversely transferred to theexcited state triplet energy levels T₁ ^(H1), T₁ ^(H2) and T₁ ^(H3) ofthe first to third hosts, which cannot utilize triplet exciton energy.Accordingly, the excitons of the triplet state level T₁ ^(TD) of thefirst dopant may be quenched as a non-emission and the triplet stateexcitons of the first dopant cannot be involved in the emission. As anexample, each of the excited state triplet energy levels T₁ ^(H1), T₁^(H2) and T₁ ^(H3) of the first to third hosts may be higher than theexcited state triplet energy level T₁ ^(TD) of the first dopant by atleast about 0.2 eV.

In addition, it is necessary for the EML 560 to implement high luminousefficiency and color purity as well as to transfer exciton energyefficiently from the first dopant, which is converted to ICT complexstate by RISC mechanism in the EML1 562, to the second and third dopantseach of which is the fluorescent or phosphorescent material in the EML2564 and the EML3 566. In order to realize such an OLED 500, the excitedstate triplet energy level T₁ ^(TD) of the first dopant in the EML1 562is higher than each of excited state triplet energy levels T₁ ^(FD1) andT₁ ^(FD2) of the second and third dopants. In one exemplary embodiment,the excited state singlet energy level S₁ ^(TD) of the first dopant maybe higher than each of excited state singlet energy levels S₁ ^(FD1) andS₁ ^(D2) of the second and third dopants as fluorescent material.

Moreover, the exciton energy, which is transferred from the first dopantto each of the second and third dopants, should not be transferred tothe second and third hosts in order to realize efficient light emission.As an example, each of the excited singlet energy levels S₁ ^(H2) and S₁^(H3) of the second and third hosts may be higher than each of theexcited state energy level S₁ ^(FD1) and S₁ ^(FD2) of the second andthird dopants, respectively. In one exemplary embodiment, the energylevel bandgap between the excited state singlet energy level S₁ ^(TD)and the excited state triplet energy level T₁ ^(TD) of the first dopantmay be equal to or less than about 0.3 eV in order to implement adelayed fluorescence.

In addition, an energy level bandgap (|HOMO^(H1)-HOMO^(TD)|) between aHOMO energy level (HOMO^(H1)) of the first host and a HOMO energy level(HOMO^(TD)) of the first dopant, or an energy level bandgap(|LUMO^(H1)-LUMO^(TD)|) between a LUMO energy level (LUMO^(H1)) of thefirst host and a LUMO energy level (LUMO^(TD)) of the first dopant maybe equal to or less than about 0.5 eV.

Each of the EML1 562, the EML2 564 and the EML3 566 may include thefirst host, the second host and the third host, respectively. Forexample, each of the first to third hosts may be the same or differentfrom each other. For Example, each of the first to third hosts mayindependently include, but is not limited to, mCP-CN, CBP, mCBP, mCP,DPEPO, PPT, TmPyPB, PYD-2Cz, DCzDBT, DCzTPA, pCzB-2CN, mCzB-2CN, TSPO1,CCP, 9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9′-bicarbazole and/or4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.

Each of the second and third dopants may have narrow FWHM and haveluminous spectrum having large overlapping area with the absorptionspectrum of the first dopant. As an example, each of the second andthird dopants may independently include, but is not limited to, anorganic compound having a quinolino-acridine core such as5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,12H)-dione,5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,12H)-dione, DCJTB and any metal complexes which can emit light of greencolor.

In one exemplary embodiment, each of the first to third hosts in theEML1 562, EML2 564 and the EML3 566 may have weigh ratio equal to ormore than the weight ratio of the first to third dopants within the sameEMLs 562, 564 and 566. The weight ratio of the first dopant in the EML1562 may be more than each of the weight ratio of the second and thirddopants in the EML2 564 and the EML3 566. In this case, it is possibleto transfer enough exciton energy from the first dopant in the EML1 562to the second and third dopants in the EML2 564 and the EML3 566 throughFRET energy transfer mechanism.

Particularly, the weight ratio of the first host may be equal to or morethan the weight ratio of the first dopant in the EML1 562. As anexample, the EML1 562 may include the first host of about 50 to about99% by weight, preferably about 60 to about 90% by weight, and morepreferably about 60 to about 80% by weight, and the first dopant ofabout 1 to about 50% by weight, preferably about 10 to about 40% byweight, and more preferably about 20 to about 40% by weight.

Each of the weight ratios of the second and thirds hosts may be largerthan each of the weight ratios of the second and third dopants in theEML2 564 and the EML3 566. As an example, each of the EML2 564 and EML3566 may include the second or third host, but is not limited to, about90 to about 99% by weight, and preferably about 95 to about 99% byweight, and the second or third dopant, but is not limited to, about 1to about 10% by weight, and preferably about 1 to about 5% by weight.

The EML1 562 may be laminated with a thickness of, but is not limitedto, about 2 nm to about 100 nm, preferably about 2 nm to about 30 nm,and preferably about 2 to about 20 nm. Each of the EML2 564 and the EML3566 may be laminated with a thickness of, but is not limited to, about 5nm to about 100 nm, preferably about 10 nm to about 30 nm, and morepreferably about 10 nm to about 20 nm.

When the EML2 564 is disposed adjacently to the EBL 555 in one exemplaryembodiment, the second host, which is included in the EML2 564 togetherwith the second dopant, may be the same material as the EBL 555. In thiscase, the EML2 564 may have an electron blocking function as well as anemission function. In other words, the EML2 564 can act as a bufferlayer for blocking electrons. In one embodiment, the EBL 555 may beomitted where the EML2 564 may be an electron blocking layer as well asan emitting material layer.

When the EML3 566 is disposed adjacently to the HBL 575 in anotherexemplary embodiment, the third host, which is included in the EML3 566together with the third dopant, may be the same material as the HBL 575.In this case, the EML3 566 may have a hole blocking function as well asan emission function. In other words, the EML3 566 can act as a bufferlayer for blocking holes. In one embodiment, the HBL 575 may be omittedwhere the EML3 566 may be a hole blocking layer as well as an emittingmaterial layer.

In still another exemplary embodiment, the second host in the EML2 564may be the same material as the EBL 555 and the third host in the EML3566 may be the same material as the HBL 575. In this embodiment, theEML2 564 may have an electron blocking function as well as an emissionfunction, and the EML3 566 may have a hole blocking function as well asan emission function. In other words, each of the EML2 564 and the EML3566 can act as a buffer layer for blocking electrons or hole,respectively. In one embodiment, the EBL 555 and the HBL 575 may beomitted where the EML2 564 may be an electron blocking layer as well asan emitting material layer and the EML3 566 may be a hole blocking layeras well as an emitting material layer.

In the above embodiments, the OLED having only one emitting unit isdescribed. Unlike the above embodiment, the OLED may have multipleemitting units so as to form a tandem structure. FIG. 11 is across-sectional view illustrating an organic light emitting diode inaccordance with still another embodiment of the present disclosure.

As illustrated in FIG. 11, the OLED 600 in accordance with the fifthembodiment of the present disclosure includes first and secondelectrodes 610 and 620 facing each other, a first emitting unit 630 as afirst emission layer disposed between the first and second electrodes610 and 620, a second emitting unit 730 as a second emission layerdisposed between the first emitting unit 630 and the second electrode620, and a charge generation layer 710 disposed between the first andsecond emitting units 630 and 730.

As mentioned above, the first electrode 610 may be an anode and include,but is not limited to, a conductive material having a relatively largework function values. As an example, the first electrode 610 mayinclude, but is not limited to, ITO, IZO, SnO, ZnO, ICO, AZO, and thelike. The second electrode 620 may be a cathode and may include, but isnot limited to, a conductive material having a relatively small workfunction values such as Al, Mg, Ca, Ag, alloy thereof or combinationthereof. Each of the first and second electrodes 610 and 620 may belaminated with a thickness of, but is not limited to, about 30 nm toabout 300 nm.

The first emitting unit 630 includes a HIL 640, a first HTL (a lowerHTL) 650, a lower EML 660 and a first ETL (a lower ETL) 670. The firstemitting unit 630 may further include a first EBL (a lower EBL) 655disposed between the first HTL 650 and the lower EML 660 and/or a firstHBL (a lower HBL) 675 disposed between the lower EML 660 and the firstETL 670.

The second emitting unit 730 includes a second HTL (an upper HTL) 750,an upper EML 760, a second ETL (an upper ETL) 770 and an EIL 780. Thesecond emitting unit 730 may further include a second EBL (an upper EBL)755 disposed between the second HTL 750 and the upper EML 760 and/or asecond HBL (an upper HBL) 775 disposed between the upper EML 760 and thesecond ETL 770.

At least one of the lower EML 660 and the upper EML 760 may include theorganic compound having the structure of any one in Chemical Formulae 1,4, 7, 8 and 11 and emit green (G) light. As an example, one of the lowerand upper EMLs 660 and 760 may emit green (G) light, and the other ofthe lower and upper EMLs 660 and 760 may emit blue (B) and/or red (R)light. Hereinafter, the OLED 600, where the lower EML 660 emits greenlight and includes the organic compound having the structure of any onein Chemical Formulae 1, 4, 7, 8 and 11 and the upper EML 760 emits blueand/or red lights, will be explained.

The HIL 640 is disposed between the first electrode 610 and the firstHTL 650 and improves an interface property between the inorganic firstelectrode 610 and the organic first HTL 650. In one exemplaryembodiment, the HIL 640 may include, but is not limited to, MTDATA,NATA, 1T-NATA, 2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN, TDAPB, PEDOT/PSSand/orN-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine.The HIL 640 may be omitted in compliance with a structure of the OLED600.

Each of the first and second HTLs 650 and 750 may independently include,but is not limited to, TPD, NPD(NPB), CBP, poly-TPD, TFB, TAPC,N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amineand/orN-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine.Each of the HIL 640 and the first and second HTLs 650 and 750 may belaminated with a thickness of, but is not limited to, about 5 nm toabout 200 nm, and preferably about 5 nm to about 100 nm.

Each of the first and second ETLs 670 and 770 facilitates electrontransportations in the first emitting unit 630 and the second emittingunit 730, respectively. Each of the first and second ETLs 670 and 770may independently include, but is not limited to, oxadiazole-basedcompounds, triazole-based compounds, phenanthroline-based compounds,benzoxazole-based compounds, benzothiazole-based compounds,benzimidazole-based compounds, triazine-based compounds, and the like,respectively. As an example, each of the first and second ETLs 670 and770 may independently include, but is not limited to, Alq₃, PBD,spiro-PBD, Liq, TPBi, BAlq, Bphen, NBphen, BCP, TAZ, NTAZ, TpPyPB,TmPPPyTz, PFNBr and/or TPQ, respectively.

The EIL 780 is disposed between the second electrode 620 and the secondETL 770, and can improve physical properties of the second electrode 620and therefore, can enhance the life span of the OLED 600. In oneexemplary embodiment, the EIL 780 may include, but is not limited to, analkali halide such as LiF, CsF, NaF, BaF₂ and the like, and/or anorganic metal compound such as lithium benzoate, sodium stearate, andthe like.

As an example, each of the first and second EBLs 655 and 755 mayindependently include, but is not limited to, TCTA,Tris[4-(diethylamino)phenyl]amine,N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine,TAPC, MTDATA, mCP, mCBP, CuPc, DNTPD, TDAPB2,8-bis(9-phneyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or3,6-bis(N-carbazolyl)-N-phenyl-carbazole, respectively.

Each of the first and second HBLs 675 and 775 may independently include,but is not limited to, oxadiazole-based compounds, triazole-basedcompounds, phenanthroline-based compounds, benzoxazole-based compounds,benzothiazole-based compounds, benzimidazole-based compounds, andtriazine-based compounds. As an example, each of the first and secondHBLs 675 and 775 may independently include, but is not limited to, BCP,BAlq, Alga, PBD, spiro-PBD, Liq, B3PYMPM, DPEPO,9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9′-bicarbazole andcombination thereof, respectively.

In one exemplary embodiment, when the upper EML 760 emits red light, theupper EML 760 may be, but is not limited to, a phosphorescent materiallayer including a host such as CBP and the like and at least one dopantselected from the group consisting of PIQIr(acac)(bis(1-phenylisoquinoline)acetylacetonate iridium). PQIr(acac)(bis(1-phenylquinoline)acetylacetonate iridium), PQIr(tris(1-phenylquinoline)iridium) and PtOEP(octaethylporphyrin platinum).Alternatively, the upper EML 760 may be a fluorescent material layerincluding PBD:Eu(DMB)₃(phen), perylene and/or their derivatives. In thiscase, the upper EML 760 may emit red light having, but is not limitedto, emission wavelength ranges of about 600 nm to about 650 nm.

In another exemplary embodiment, when the upper EML 760 emits bluelight, the upper EML 760 may be, but is not limited to, a phosphorescentmaterial layer including a host such as CBP and the like and at leastone iridium-based dopant. Alternatively, the upper EML 760 may be afluorescent material layer including any one selected from the groupconsisting of spiro-DPVBi, spiro-CBP, distrylbenzene (DSB),distrylarylene (DSA), PFO-based polymers and PPV-based polymers. Theupper EML 760 may emit light of sky-blue color or deep blue color aswell as blue color. In this case, the upper EML 760 may emit red lighthaving, but is not limited to, emission wavelength ranges of about 440nm to about 480 nm.

In one exemplary embodiment, the second emitting unit 730 may havedouble-layered EML 760, for example, a blue emitting material layer anda red emitting material layer, in order to enhance luminous efficiencyof the red light. In this case, the upper EML 760 may emit light having,but is not limited to, emission wavelength ranges of about 440 nm toabout 650 nm.

The charge generation layer (CGL) 710 is disposed between the firstemitting unit 630 and the second emitting unit 730. The CGL 710 includean N-type CGL 810 disposed adjacently to the first emitting unit 630 anda P-type CGL 820 disposed adjacently to the second emitting unit 730.The N-type CGL 810 injects electrons into the first emitting unit 630and the P-type CGL 820 injects holes into the second emitting unit 730.

As an example, the N-type CGL 810 may be a layer doped with an alkalimetal such as Li, Na, K and/or Cs and/or an alkaline earth metal such asMg, Sr, Ba and/or Ra. For example, a host used in the N-type CGL 810 mayinclude, but is not limited to, an organic compound such as Bphen orMTDATA. The alkali metal or the alkaline earth metal may be doped byabout 0.01 wt % to about 30 wt %.

The P-type CGL 820 may include, but is not limited to, an inorganicmaterial selected from the group consisting of tungsten oxide (WO_(x)),molybdenum oxide (MoO_(x)), beryllium oxide (Be₂O₃), vanadium oxide(V₂O₅) and combination thereof, and/or an organic material selected fromthe group consisting of NPD, HAT-CN,2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), TPD,N,N,N′,N′-Tetranaphthalenyl-benzidine (TNB), TCTA,N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) and combinationthereof.

The lower EML 660 includes a first EML (EML1) 662 disposed between thefirst EBL 655 and the first HBL 675, a second EML (EML2) 664 disposedbetween the first EBL 655 and the EML1 662 and a third EML (EML3) 666disposed between the EML1 662 and the first HBL 675. The EML1 662includes a first dopant (T dopant) which is a delayed fluorescentmaterial. i.e. the organic compound having the structure of any one inChemical Formulae 1, 4, 7, 8 and 11. Each of the EML2 664 and the EML3666 includes a second dopant (a first F dopant) and a third dopant (asecond F dopant) each of which is a fluorescent or phosphorescentmaterial, respectively. Each of the EML1 662, the EML2 664 and the EML3666 includes a first host, a second host and a third host, respectively.

In this case, the singlet exciton energy as well as the triplet excitonenergy of the first dopant in the EML1 662 can be transferred to each ofthe second and third dopants each of which is included in the EML2 664and EML3 666 disposed adjacently to the EML1 662 by FRET energy transfermechanism. Accordingly, the ultimate emission occurs in the second andthird dopants in the EML2 664 and the EML3 666.

In other words, the triplet exciton energy of the first dopant isconverted to the singlet exciton energy of its own in the EML1 662 byRISC mechanism, then the singlet exciton energy of the first dopant istransferred to each of the singlet exciton energy of the second andthird dopants because the excited state singlet energy level S₁ ^(TD) ofthe first dopant is higher than each of the excited state singlet energylevels S₁ ^(FD1) and S₁ ^(FD2) of the second and third dopants (See,FIG. 10).

The second and third dopants in the EML2 664 and EML3 666 can emit lightusing the singlet exciton energy and the triplet exciton energy derivedfrom the first dopant. Since the second and third dopants haverelatively narrow FWHM as compared with the first dopant, the OLED 600can enhance its luminous efficiency and color purity.

Each of the EML1 662, the EML2 664 and the EML3 666 includes the firsthost, the second host and the third host, respectively. For example,each of the first to third hosts may be the same or different from eachother. As an example, each of the first to third hosts may independentlyinclude, but is not limited to, mCP-CN, CBP, mCBP, mCP, DPEPO, PPT,TmPyPB, PYD-2Cz, DCzDBT, DCzTPA, pCzB-2CN, mCzB-2CN, TSPO1, CCP,9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9′-bicarbazole,9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9′-bicarbazole and/or4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.

Each of the second and third dopants may have narrow FWHM and haveluminous spectrum having large overlapping area with the absorptionspectrum of the first dopant. As an example, each of the second andthird dopants may independently include, but is not limited to, anorganic compound having a quinolino-acridine core such as5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-dibutyl-3,10-di fluoroquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,12H)-dione,5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,12H)-dione, DCJTB and any metal complexes which can emit light of greencolor.

In this case, the energy levels among the first to third hosts and thefirst to third dopant within the lower EML 660 are the same as describedin FIG. 10.

In one exemplary embodiment, each of the first to third hosts in theEML1 662, EML2 664 and the EML3 666 may have weigh ratio equal to ormore than the weight ratio of the first to third dopants within the sameEMLs 662, 664 and 666. The weight ratio of the first dopant in the EML1662 may be more than each of the weight ratio of the second and thirddopants in the EML2 664 and the EML3 666. In this case, it is possibleto transfer enough exciton energy from the first dopant in the EML1 662to the second and third dopants in the EML2 664 and the EML3 666 throughFRET energy transfer mechanism.

When the EML2 664 is disposed adjacently to the first EBL 655 in oneexemplary embodiment, the second host, which is included in the EML2 664together with the second dopant, may be the same material as the firstEBL 655. In this case, the EML2 664 may have an electron blockingfunction as well as an emission function. In other words, the EML2 664can act as a buffer layer for blocking electrons. In one embodiment, thefirst EBL 655 may be omitted where the EML2 664 may be an electronblocking layer as well as an emitting material layer.

When the EML3 666 is disposed adjacently to the first HBL 675 in anotherexemplary embodiment, the third host, which is included in the EML3 666together with the third dopant, may be the same material as the firstHBL 675. In this case, the EML3 666 may have a hole blocking function aswell as an emission function. In other words, the EML3 666 can act as abuffer layer for blocking holes. In one embodiment, the first HBL 675may be omitted where the EML3 666 may be a hole blocking layer as wellas an emitting material layer.

In still another exemplary embodiment, the second host in the EML2 664may be the same material as the first EBL 655 and the third host in theEML3 666 may be the same material as the first HBL 675. In thisembodiment, the EML2 664 may have an electron blocking function as wellas an emission function, and the EML3 666 may have a hole blockingfunction as well as an emission function. In other words, each of theEML2 664 and the EML3 666 can act as a buffer layer for blockingelectrons or hole, respectively. In one embodiment, the first EBL 655and the first HBL 675 may be omitted where the EML2 664 may be anelectron blocking layer as well as an emitting material layer and theEML3 666 may be a hole blocking layer as well as an emitting materiallayer.

In an alternative embodiment, the lower EML 660 may have asingle-layered structure as illustrated in FIGS. 2 and 5. In this case,the lower EML 660 may include a host and a first dopant which may be adelayed fluorescent material, i.e. the organic compound having thestructure of any one in Chemical Formulae 1, 4, 7, 8 and 11.Alternatively, the lower EML 660 may include a host, a first dopantwhich may be a delayed fluorescent material and a second dopant whichmay be a fluorescent or phosphorescent material.

In another alternative embodiment, the lower EML 660 may have adouble-layered structure as illustrated in FIG. 7. In this case, thelower EML 660 may include a first EML and a second EML. The first EMLmay include a first host and a first dopant which may be a delayedfluorescent material, i.e. the organic compound having the structure ofany one in Chemical Formulae 1, 4, 7, 8 and 11, and the second EML mayinclude a second host and a second dopant which may be a fluorescent orphosphorescent material.

In another exemplary embodiment, an OLED of the present disclosure mayfurther includes a third emitting unit disposed between the secondemitting unit 730 and the second electrode 620 and a second CGL disposedbetween the second emitting unit 730 and the third emitting unit. Inthis case, at least one of the first emitting unit 630, the secondemitting unit 730 and the third emitting unit may include the organiccompound having the structure of any one in Chemical Formulae 1, 4, 7, 8and 11 as the dopant.

Synthesis Example 1: Synthesis of Compound 1-2 (1) Synthesis ofIntermediate A1

10 g (1 equivalent) of 2-chloro-4,6-diphenyl-1,3,5-triazine wasdissolved in 80 mL of 1,4-dioxane with stirring under nitrogenatmosphere. 28.46 g (3 equivalents) of bis(pinacolato)diboron, 1 g (0.03equivalent) of tris(dibenzylideneacetone) dipalladium (0) (Pd₂(dba)₃),0.24 g (0.1 equivalent) of2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (Xphos) and 11 g(3 equivalents) of potassium acetate were added into the solution, andthen the solution was refluxed with stirring for more than 12 hours toproceed a reaction. After the reaction was completed, the solution wascooled down to room temperature, was extracted with ethyl acetate anddistilled water, and then MgSO₄ was added into the organic solution toremove moisture. A crude extract was separated and isolated by columnchromatography using hexane and ethyl acetate (4:1) as a developingsolvent and was re-crystallized to give 10.2 g of Intermediate A1(yield: 72%).

(2) Synthesis of Intermediate A2

19.24 g (5 equivalents) of potassium carbonate was dissolved in 50 mL ofwater. 10 g (1 equivalent) of Intermediate A1, 8.35 g (1.5 equivalents)of 2-bromo-5-fluorobenzonitrile, 1.61 g (0.05 equivalent) oftetrakis(triphenylphosphine) palladium (0) (Pd(PPh₃)₄) and 150 mL of THFwas added into the aqueous solution, and then the mixed solution wasrefluxed with stirring for more than 96 hours to proceed to a reaction.After the reaction was completed, the solution was cooled down to roomtemperature, was extracted with ethyl acetate and distilled water, andthen MgSO₄ was added into the organic solution to remove moisture. Acrude extract was separated and purified by column chromatography usinghexane and methylene chloride (3:1) as a developing solvent and wasre-crystallized to give 6.4 g of Intermediate A2 (yield: 65%).

(3) Synthesis of Intermediate D1

10 g (1 equivalent) of 1-bromo-2-iodobenzene, 3.6 mL (1 equivalent) ofaniline, 0.4 g (0.05 equivalent) of Pd₂(dba)₃, 1 mL (0.1 equivalent) oftri-tert-butylphosphine and 5.1 g (5 equivalents) ofsodium-tert-butoxide was suspended in 120 mL of toluene, and then thesuspension was refluxed with stirring for 20 hours. After the reactionwas completed, the suspension was extracted with methylene chloride anddistilled water and then organic layer was distilled under reducedpressure. A crude extract was separated and purified by columnchromatography using hexane and methylene chloride (5:1) as a developingsolvent and was re-crystallized to give 7.5 g of Intermediate D1 (yield:85%).

(4) Synthesis of Intermediate D2

7.5 g of intermediate D1 was added into 80 mL of THF under nitrogenatmosphere, and then the solution was cooled down to −78° C. using dryice. 24 mL of 2.5 M n-BuLi was added into the solution drop wisely andthen the solution was stirred for 1 hour. 5.88 g of xanthone dissolvedin 50 mL of THF was added into the solution. After removing solvents,100 mL of acetic acid/HCl (1:10 v/v) was added to give 8.35 g ofIntermediate D2 (yield: 80%).

(5) Synthesis of Compound 1-2

1.92 g (1.3 equivalents) of Intermediate D2 was placed into a reactionvessel under nitrogen atmosphere, then 50 mL of dimethyl formamide wasadded into the reaction vessel, and then the solution was stirred. 0.74g (3 equivalents) of sodium hydride (55%) dispersed in paraffin wasadded into the solution. After the solution was stirred enough togenerate hydrogen gas, 1.50 g of intermediate A2 was added into thesolution, and the solution was refluxed with stirring for more than 96hours at 160° C. The solution was cooled down to room temperature,dimethyl formamide was evaporated and then the solution was filteredwith toluene. A crude product was separated and purified by columnchromatography using hexane and toluene (1:3) as a developing solventand was re-crystallized to give 1.15 g of white solid Compound 1-2(yield: 74%).

Synthesis Example 2: Synthesis of Compound 1-16 (1) Synthesis ofIntermediate A3

g (4 equivalents) of potassium carbonate was dissolved in 30 mL ofwater. 5 g (1 equivalent) of intermediate A1, 3.34 g (1.2 equivalents)of 5-bromo-2-fluorobenzonitrile, 0.85 g (0.05 equivalent) of Pd(PPh₃)₄and 90 mL of THF was added into the aqueous solution, and then the mixedsolution was refluxed with stirring for more than 96 hours to proceed toa reaction. After the reaction was completed, the solution was cooleddown to room temperature, was extracted with ethyl acetate and distilledwater, and then MgSO₄ was added into the solution to remove moisture. Acrude extract was separated and purified by column chromatography usinghexane and methylene chloride (3:1) as a developing solvent and wasre-crystallized to give 3.8 g of Intermediate A3 (yield: 78%).

(2) Synthesis of Intermediate D3

7.5 g of intermediate D1 was added into 80 mL of THF under nitrogenatmosphere, and then the solution was cooled down to −78° C. using dryice. 24 mL of 2.5 M n-BuLi was added into the solution drop wisely andthen the solution was stirred for 1 hour. 5.6 g of 9-fluorneonedissolved in 50 mL of THF wad added into the solution. After removingsolvents, 100 mL of acetic acid/HCl (1:10 v/v) was added to give 7.19 gof Intermediate D3 (yield: 78%).

(3) Synthesis of Compound 1-16

2.11 g (1.5 equivalents) of Intermediate D3 was placed into a reactionvessel under nitrogen atmosphere, then 50 mL of dimethyl formamide wasadded into the reaction vessel, and then the solution was stirred. 0.74g (3 equivalents) of sodium hydride (55%) dispersed in paraffin wasadded into the solution. After the solution was stirred enough togenerate hydrogen gas, 1.50 g (1 equivalent) of Intermediate A3 wasadded into the solution, and the solution was refluxed with stirring formore than 96 hours at 160° C. The solution was cooled down to roomtemperature, dimethyl formamide was evaporated and then the solution wasfiltered with toluene. A crude product was separated and purified bycolumn chromatography using hexane and toluene (1:3) as a developingsolvent and was re-crystallized to give 1.27 g of white solid Compound1-16 (yield: 82%).

Synthesis Example 3: Synthesis of Compound 1-17

1.92 g (1.3 equivalents) of Intermediate D2 was placed into a reactionvessel under nitrogen atmosphere, then 50 mL of dimethyl formamide wasadded into the reaction vessel, and then the solution was stirred. 0.74g (3 equivalents) of sodium hydride (55%) dispersed in paraffin wasadded into the solution. After the solution was stirred enough togenerate hydrogen gas, 1.50 g of Intermediate A3 was added into thesolution, and the solution was refluxed with stirring for more than 96hours at 160° C. The solution was cooled down to room temperature,dimethyl formamide was evaporated and then the solution was filteredwith toluene. A crude product was separated and purified by columnchromatography using hexane and toluene (1:3) as a developing solventand was re-crystallized to give 1.11 g of white solid Compound 1-17(yield: 71%).

Synthesis Example 4: Synthesis of Compound 2-1 (1) Synthesis ofIntermediate A4

8.65 g (4.5 equivalents) of potassium carbonate was dissolved in 30 mLof water. 5 g (1 equivalent) of Intermediate A1, 3.76 g (1.2equivalents) of 5-bromo-2-fluoroisophthalonitrile, 1.19 g (0.07equivalent) of Pd(PPh₃)₄ and 80 mL of THF was added into the aqueoussolution, and then the mixed solution was refluxed with stirring formore than 96 hours to proceed to a reaction. After the reaction wascompleted, the solution was cooled down to room temperature, wasextracted with ethyl acetate and distilled water, and then MgSO₄ wasadded into the organic solution to remove moisture. A crude extract wasseparated and purified by column chromatography using hexane andmethylene chloride (5:2) as a developing solvent and was re-crystallizedto give 3.8 g of white solid Intermediate A4 (yield: 78%).

(2) Synthesis of Compound 2-1

2.1 g (1.5 equivalents) of Intermediate D3 was placed into a reactionvessel under nitrogen atmosphere, then 50 mL of dimethyl formamide wasadded into the reaction vessel, and then the solution was stirred. 0.74g (3 equivalents) of sodium hydride (55%) dispersed in paraffin wasadded into the solution. After the solution was stirred enough togenerate hydrogen gas, 1.60 g (1 equivalent) of Intermediate A4 wasadded into the solution, and the solution was refluxed with stirring formore than 96 hours at 160° C. The solution was cooled down to roomtemperature, dimethyl formamide was evaporated and then the solution wasfiltered with toluene. A crude product was separated and purified bycolumn chromatography using hexane and toluene (2:5) as a developingsolvent and was re-crystallized to give 0.89 g of white solid Compound2-1 (yield: 57%).

Experimental Example 1: Evaluation of Energy Levels

Energy levels for the Compounds in the Synthesis Examples 1 to 4 wereevaluated. Particularly, HOMO energy level, LUMO energy level and energylevel bandgap (Eg)) for each of the compounds were evaluated. For thecomparison, energy levels for the following referenced compounds werealso evaluated. The evaluation results are indicated in the followingtable 1. As indicated by Table 1, each of Compounds in the SynthesisExamples 1 to 4 showed an adequate HOMO energy level, LUMO energy leveland energy level bandgap as used a luminous material, i.e. a dopant inan emitting layer of an organic light emitting diode.

Referenced Compounds

TABLE 1 Energy Levels of Organic Compound Compound HOMO (eV) LUMO (eV)Eg (eV) Ref. 1 −5.3 −2.5 2.80 Ref. 2 −5.2 −2.4 2.84 Ref. 3 −5.3 −2.62.75 Compound 1-2 −5.3 −2.7 2.68 Compound 1-16 −5.4 −2.8 2.66 Compound1-17 −5.4 −2.7 2.70 Compound 2-1 −5.5 −2.8 2.72 HOMO: Film (100 nm/ITO),by AC3, LUMO: calculated from film absorption edge; Eg: LUMO-HOMO

Example 1: Fabrication of Organic Light Emitting Diode (OLED)

An organic light emitting diode was fabricated using Compound 1-2synthesized in the Synthesis Example 1 as a dopant in an emittingmaterial layer (EML). An ITO substrate was treated with UV ozone andthen loaded into an evaporation system. The cleaned substrate wastransferred to a deposition chamber in order to deposit other layers onthe substrate. An organic layer was deposited by evaporation by a heatedboat under 10⁻⁶ torr in the following order:

A hole injection layer (HIL) (HAT-CN; 7 nm); a hole transport layer(HTL) (NPB, 55 nm); an electron blocking layer (EBL) (mCBP; 10 nm); anemitting material layer (EML)(4-(3-triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene (host): Compound 1-2(dopant)=70:30 by weight ratio; 35 nm); a hole blocking layer (HBL)(B3PYMPM; 10 nm); an electron transport layer (ETL) (TPBi; 20 nm); anelectron injection layer (EIL) (LiF); and a cathode (Al).

And then, capping layer (CPL) was deposited over the cathode and thedevice was encapsualted by glass. After deposition of emissve layer andthe cathode, the OLED was transferred from the depostion chamber to adry box for film formation, followed by encapsulation using UV-curableepoxy and moisture getter. The manufactured organic light emitting diodehad an emision area of 9 mm².

Examples 2 to 4: Fabrication of OLED

An organic light emitting diode was manufactured as the same process andthe same materials as Example 1, except using compound 1-16 (Example 2),Compound 1-17 (Example 3) or Compound 2-1 (Example 4) as the dopant inplace of Compound 1-2 in the EML.

Comparative Examples 1 to 3: Manufacture of OLED

An organic light emitting diode was manufactured as the same process andthe same materials as Example 1, except using Ref 1 (Comparative Example1; Ref. 1), Ref. 2 (Comparative Example 2; Ref. 2) or Ref. 3(Comparative Example 3; Ref. 3) as the dopant in placed of Compound 1-2in the EML.

Experimental Example 2: Measurement of Luminous Properties of OLED

Each of the organic light emitting diodes fabricated in Examples 1 to 4and Comparative Examples 1 to 3 was connected to an external powersource and then luminous properties for all the diodes were evaluatedusing a constant current source (KEITHLEY) and a photometer PR650 atroom temperature. In particular, current efficiency (cd/A), externalquantum efficiency (EQE; %), maximum electroluminescence wavelength (ELλ_(max); nm) and color coordinates at a current density of 10 mA/cm² forthe OLEDs were measured. The results thereof are shown in the followingTable 2.

TABLE 2 Luminous Properties of OLED Sample cd/A EQE (%) EL λ_(max) (nm)CIE Ref. 1 3.99 2.17 480 (0.168, 0.260) Ref. 2 7.88 4.80 468 (0.156,0.224) Ref. 3 19.14 6.51 514 (0.258, 0.491) Example 1 56.90 17.40 520(0.325, 0.512) Example 2 73.10 21.65 528 (0.330, 0.521) Example 3 61.1018.73 520 (0.327, 0.516) Example 4 45.64 15.03 518 (0.291, 0.546)

As indicated in Table 2, compared with the OLED using organic compoundshaving a triazine core as the dopant in the EML of the ComparativeExamples, the OLED using the organic compounds of the present disclosureas the dopant in the EML of the Examples improved its current efficiencyup to 17.32 times and EQE up to 8.98 times. Compared to the OLED usingthe compounds having a Spiro moiety substituted with cyano group as thedopant in the Comparative Examples 2 and 3, the OLED using the organiccompound of the present disclosure as the dopant in the Examplesimproved its current efficiency up to 8.28 times and EQE up to 3.51times. Also, compared the EL λ_(max) and CIEs in the Examples with theEL λ_(max) and CIEs in the Comparative Examples, it was confirmed thatthe OLEDs in the Examples 1-4 emit light having a deeper green color. Itwas confirmed that the OLED can implement hyper-fluorescence havingenhanced luminous efficiency and high color purity by applying theorganic compounds of the present disclosure into an emission layer.

While the present disclosure has been described with reference toexemplary embodiments and examples, these embodiments and examples arenot intended to limit the scope of the present disclosure. Rather, itwill be apparent to those skilled in the art that various modificationsand variations can be made in the present disclosure without departingfrom the spirit or scope of the invention. Thus, it is intended that thepresent disclosure cover the modifications and variations of the presentdisclosure provided they come within the scope of the appended claimsand their equivalents.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

The invention claimed is:
 1. An organic compound having the followingstructure of Chemical Formula 1:

wherein each of R₁ to R₅ is independently protium, deuterium, tritium,halogen, C₁˜C₁₀ alkyl halide, cyano group, nitro group or a moietyhaving the following structure of Chemical Formula 2 or Chemical Formula3, wherein at least one of R₁ to R₅ is selected from the groupconsisting of halogen, C₁˜C₁₀ alkyl halide, cyano group and nitro groupand at least one of R₁ to R₅ is a moiety of Chemical Formula 2 orChemical Formula 3; each of R₆ and R₇ is independently C₅˜C₃₀ aryl groupor C₄˜C₃₀ hetero aryl group:

wherein each of R₈ and R₉ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ aryl group, C₄˜C₃₀ hetero arylgroup, C₅˜C₃₀ aryl amino group and C₄˜C₃₀ hetero aryl amino group,wherein each of the C₅˜C₃₀ aryl group, the C₄˜C₃₀ hetero aryl group, theC₅˜C₃₀ aryl amino group and the C₄˜C₃₀ hetero aryl amino group isunsubstituted or substituted with an aromatic group, a hetero aromaticgroup or a combination thereof, respectively; each of a and b is anumber of a substituent and is independently an integer of 1 to 3; X inChemical Formula 3 is CR₁₁R₁₂, NR₁₃, SiR₁₄R₁₅, oxygen (O) or sulfur (S),wherein each of R₁₁ to R₁₅ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ aryl group and C₄˜C₃₀ heteroaryl group.
 2. The organic compound of claim 1, wherein the organiccompound has the following structure of Chemical Formula 4:

wherein R₂₁ is cyano group; and R₂₂ is a moiety having the followingstructure of Chemical Formula 5 or Chemical Formula 6:

wherein each of R₂₃ and R₂₄ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₅˜C₃₀aryl group unsubstituted or substituted with an aromatic group, a heteroaromatic group or a combination thereof, and C₄˜C₃₀ hetero aryl groupunsubstituted or substituted with an aromatic group, a hetero aromaticgroup or a combination thereof; X in Chemical Formula 6 is CR₁₁R₁₂,NR₁₃, SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁ to R₁₅ isindependently selected from the group consisting of protium, deuterium,tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group,C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.
 3. The organic compoundof claim 2, wherein the organic compound has the following structure ofChemical Formula 7,


4. The organic compound of claim 2, wherein the organic compound has aHOMO energy level between about −5.0 and about −6.0 eV, and a LUMOenergy level between about −2.5 and about −3.5 eV; and wherein an energybandgap between the HOMO energy level and the LUMO energy level isbetween about 2.2 to about 3.0 eV.
 5. The organic compound of claim 1,wherein the organic compound has the following structure of ChemicalFormula 8:

wherein each of R₃₁ and R₃₂ is a cyano group; and R₃₃ is a moiety havingthe following structure of Chemical Formula 9 or Chemical Formula 10:

wherein each of R₃₄ and R₃₅ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₅˜C₃₀aryl group unsubstituted or substituted with an aromatic group, a heteroaromatic group or a combination thereof, and C₄˜C₃₀ hetero aryl groupunsubstituted or substituted with an aromatic group, a hetero aromaticgroup or a combination thereof; X in Chemical Formula 9 is CR₁₁R₁₂,SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁ to R₁₅ isindependently selected from the group consisting of protium, deuterium,tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group,C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.
 6. The organic compoundof claim 5, wherein the organic compound has the following structure ofChemical Formula 11,


7. The organic compound of claim 5, wherein the organic compound has aHOMO energy level between about −5.0 and about −6.0 eV, and a LUMOenergy level between about −2.5 and about −3.5 eV; and wherein an energybandgap between the HOMO energy level and the LUMO energy level isbetween about 2.2 to about 3.0 eV.
 8. The organic compound of claim 1,wherein the organic compound has a HOMO energy level between about −5.0and about −6.0 eV, and a LUMO energy level between about −2.5 and about−3.5 eV; and wherein an energy bandgap between the HOMO energy level andthe LUMO energy level is between about 2.2 to about 3.0 eV.
 9. Anorganic light emitting diode, comprising: a first electrode; a secondelectrode, wherein the first electrode and second electrode face eachother; and at least one emitting unit comprising an emitting materiallayer disposed between the first and second electrodes, wherein theemitting material layer comprises an organic compound having thefollowing structure of Chemical Formula 1:

wherein each of R₁ to R₅ is independently protium, deuterium, tritium,halogen, C₁˜C₁₀ alkyl halide, cyano group, nitro group or a moietyhaving the following structure of Chemical Formula 2 or Chemical Formula3, wherein at least one of R₁ to R₅ is selected from the groupconsisting of halogen, C₁˜C₁₀ to alkyl halide, cyano group and nitrogroup, and at least one of R₁ to R₅ is a moiety of Chemical Formula 2 orChemical Formula 3; each of R₆ and R₇ is independently C₅˜C₃₀ aryl groupor C₄˜C₃₀ hetero aryl group:

wherein each of R₈ and R₉ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ aryl group, C₄˜C₃O hetero arylgroup, C₅˜C₃₀ aryl amino group and C₄˜C₃₀ hetero aryl amino group,wherein each of the C₅˜C₃₀ aryl group, the C₄˜C₃₀ hetero aryl group, theC₅˜C₃₀ aryl amino group and the C₄˜C₃₀ hetero aryl amino group isunsubstituted or substituted with an aromatic group, a hetero aromaticgroup or a combination thereof, respectively; each of a and b is anumber of a substituent and is independently an integer of 1 to 3; X inChemical Formula 3 is CR₁₁R₁₂, NR₁₃, SiR₁₄R₁₅, oxygen (O) or sulfur (S),wherein each of R₁₁ to R₁₅ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀alkoxy group, C₁˜C₂₀ silyl group, C₅˜C₃₀ aryl group and C₄˜C₃₀ heteroaryl group.
 10. The organic light emitting diode of claim 9, wherein theorganic compound has the following structure of Chemical Formula 4:

wherein R₂₁ is cyano group; and R₂₂ is a moiety having the followingstructure of Chemical Formula 5 or Chemical Formula 6:

wherein each of R₂₃ and R₂₄ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₅˜C₃₀aryl group unsubstituted or substituted with aromatic group, heteroaromatic group or combination thereof and C₄˜C₃₀ hetero aryl groupunsubstituted or substituted with aromatic group, hetero aromatic groupor combination thereof; X in Chemical Formula 6 is CR₁₁R₁₂, NR₁₃,SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁ to R₁₅ isindependently selected from the group consisting of protium, deuterium,tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group,C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.
 11. The organic lightemitting diode of claim 9, wherein the organic compound has thefollowing structure of Chemical Formula 8:

wherein each of R₃₁ and R₃₂ is cyano group; and R₃₃ is a moiety havingthe following structure of Chemical Formula 9 or Chemical Formula 10:

wherein each of R₃₄ and R₃₅ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₅˜C₃₀aryl group unsubstituted or substituted with aromatic group, heteroaromatic group or combination thereof, and C₄˜C₃₀ hetero aryl groupunsubstituted or substituted with aromatic group, hetero aromatic groupor combination thereof; X in Chemical Formula 9 is CR₁₁R₁₂, NR₁₃,SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁ to R₁₅ isindependently selected from the group consisting of protium, deuterium,tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group,C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.
 12. The organic lightemitting diode of claim 9, wherein the emitting material layer includesa first host and a first dopant, and wherein the first dopant comprisesthe organic compound.
 13. The organic light emitting diode of claim 12,wherein an energy level bandgap (|HOMO^(H)-HOMO^(TD)|) between a HighestOccupied Molecular Orbital energy level (HOMO^(H)) of the first host anda Highest Occupied Molecular Orbital energy level (HOMO^(TD)) of thefirst dopant or an energy level bandgap (|LUMO^(H)-LUMO^(TD)|) between aLowest Unoccupied Molecular Orbital energy level (LUMO^(H)) of the firsthost and a Lowest Unoccupied Molecular Orbital energy level (LUMO^(TD))of the first dopant is equal to or less than about 0.5 eV.
 14. Theorganic light emitting diode of claim 12, wherein each of an excitedstate singlet energy level (S₁ ^(H)) and an excited state triplet energylevel (T₁ ^(H)) of the first host is higher than each of an excitedstate singlet energy level (S₁ ^(TD)) and an excited state tripletenergy level (T₁ ^(TD)) of the first dopant, respectively.
 15. Theorganic light emitting diode of claim 12, wherein the emitting materiallayer further comprises a second dopant, wherein an excited statetriplet energy level (T₁ ^(TD)) of the first dopant is lower than anexcited state triplet energy level (T₁ ^(H)) of the first host and anexcited state singlet energy level (S₁ ^(TD)) of the first dopant ishigher than an excited state singlet energy level (S₁ ^(FD)) of thesecond dopant.
 16. The organic light emitting diode of claim 9, whereinthe emitting material layer comprises a first emitting material layerdisposed between the first and second electrodes, wherein the firstemitting material comprises the organic compound, wherein the emittingmaterial layer further comprises a second emitting material layerdisposed between the first electrode and the first emitting materiallayer or between the first emitting material layer and the secondelectrode.
 17. The organic light emitting diode of claim 16, wherein thefirst emitting material layer comprises a first host and a first dopant,and wherein the first dopant comprises the organic compound.
 18. Theorganic light emitting diode of claim 17, wherein the second emittingmaterial layer comprises a second host and a second dopant.
 19. Theorganic light emitting diode of claim 18, wherein an excited statesinglet energy level (S₁ ^(TD)) of the first dopant is higher than anexcited state singlet energy level (S₁ ^(FD)) of the second dopant. 20.The organic light emitting diode of claim 18, wherein each of an excitedstate singlet energy level (S₁ ^(H1)) and an excited state tripletenergy level (T₁ ^(H1)) of the first host is higher than each of anexcited state singlet energy level (S₁ ^(TD)) and an excited statetriplet energy level (T₁ ^(TD)) of the first dopant, respectively, andwherein an excited state singlet energy level (S₁ ^(H2)) of the secondhost is higher than an excited state singlet energy level (S₁ ^(FD)) ofthe second dopant.
 21. The organic light emitting diode of claim 18,wherein the second emitting material layer is disposed between the firstelectrode and the first emitting material layer, and wherein the organiclight emitting diode further comprises an electron blocking layerdisposed between the first electrode and the second emitting materiallayer.
 22. The organic light emitting diode of claim 21, wherein thesecond host is the same as a material of the electron blocking layer.23. The organic light emitting diode of claim 18, wherein the secondemitting material layer is disposed between the first emitting materiallayer and the second electrode, and wherein the organic light emittingdiode further comprises a hole blocking layer disposed between thesecond emitting material layer and the second electrode.
 24. The organiclight emitting diode of claim 23, wherein the second host is the same asa material of the hole blocking layer.
 25. The organic light emittingdiode of claim 16, wherein the emitting material layer further comprisesa third emitting material layer disposed opposite to the second emittingmaterial layer with respect to the first emitting material layer. 26.The organic light emitting diode of claim 25, wherein the first emittingmaterial layer comprises a first host and a first dopant, and whereinthe first dopant comprises the organic compound.
 27. The organic lightemitting diode of claim 26, wherein the second emitting material layercomprises a second host and a second dopant and the third emittingmaterial layer comprises a third host and a third dopant.
 28. Theorganic light emitting diode of claim 27, wherein an excited statesinglet energy level (S₁ ^(TD)) of the first dopant is higher than eachof excited state singlet energy levels (S₁ ^(FD1) and S₁ ^(FD2)) of thesecond and third dopants, respectively.
 29. The organic light emittingdiode of claim 27, wherein each of an excited state singlet energy level(S₁ ^(H1)) and an excited state triplet energy level (T₁ ^(H1)) of thefirst host is higher than each of an excited state singlet energy level(S₁ ^(TD)) and an excited state triplet energy level (T₁ ^(TD)) of thefirst dopant, respectively, wherein an excited state singlet energylevel (S₁ ^(H2)) of the second host is higher than an excited statesinglet energy level (S₁ ^(FD1)) of the second dopant, and wherein anexcited state singlet energy level (S₁ ^(H3)) of the third host ishigher than an excited state singlet energy level (S₁ ^(FD2)) of thethird dopant.
 30. The organic light emitting diode of claim 27, whereinthe second emitting material layer is disposed between the firstelectrode and the first emitting material layer and the third emittingmaterial layer is disposed between the first emitting material layer andthe second electrode, and wherein the organic light emitting diodefurther comprises an electron blocking layer disposed between the firstelectrode and the second emitting material layer.
 31. The organic lightemitting diode of claim 30, wherein the second host is the same as amaterial of the electron blocking layer.
 32. The organic light emittingdiode of claim 27, wherein the second emitting material layer isdisposed between the first electrode and the first emitting materiallayer, and wherein the third emitting material layer is disposed betweenthe first emitting material layer and the second electrode, and whereinthe organic light emitting diode further comprises a hole blocking layerdisposed between the third emitting material layer and the secondelectrode.
 33. The organic light emitting diode of claim 32, wherein thethird host is the same as a material of the hole blocking layer.
 34. Theorganic light emitting diode of claim 33, further comprising an electronblocking layer disposed between the first electrode and the secondemitting material layer, wherein the second host is a same as a materialof the electron blocking layer.
 35. The organic light emitting diode ofclaim 9, wherein the at least one emitting unit includes a firstemitting unit disposed between the first and second electrodes andincluding a lower emitting material layer and a second emitting unitdisposed between the first emitting unit and the second electrode andincluding an upper emitting material layer, and wherein at least one ofthe lower emitting material layer and the upper emitting material layerincludes the organic compound, and further comprises a charge generationlayer disposed between the first and second emitting units.
 36. Theorganic light emitting diode of claim 35, wherein the organic compoundincludes an organic compound having the following structure of ChemicalFormula 4:

wherein R₂₁ is cyano group; and R₂₂ is a moiety having the followingstructure of Chemical Formula 5 or Chemical Formula 6:

wherein each of R₂₃ and R₂₄ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₅˜C₃₀aryl group unsubstituted or substituted with aromatic group, heteroaromatic group or combination thereof and C₄˜C₃₀ hetero aryl groupunsubstituted or substituted with aromatic group, hetero aromatic groupor combination thereof; X in Chemical Formula 6 is CR₁₁R₁₂, NR₁₃,SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁ to R₁₅ isindependently selected from the group consisting of protium, deuterium,tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group,C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.
 37. The organic lightemitting diode of claim 35, wherein the organic compound includes anorganic compound having the following structure of Chemical Formula 8:

wherein each of R₃₁ and R₃₂ is cyano group; and R₃₃ is a moiety havingthe following structure of Chemical Formula 9 or Chemical Formula 10:

wherein each of R₃₄ and R₃₅ is independently selected from the groupconsisting of protium, deuterium, tritium, C₁˜C₂₀ alkyl group, C₅˜C₃₀aryl group unsubstituted or substituted with aromatic group, heteroaromatic group or combination thereof and C₄˜C₃₀ hetero aryl groupunsubstituted or substituted with aromatic group, hetero aromatic groupor combination thereof; X in Chemical Formula 9 is is CR₁₁R₁₂, NR₁₃,SiR₁₄R₁₅, oxygen (O) or sulfur (S), wherein each of R₁₁ to R₁₅ isindependently selected from the group consisting of protium, deuterium,tritium, C₁˜C₂₀ alkyl group, C₁˜C₂₀ alkoxy group, C₁˜C₂₀ silyl group,C₅˜C₃₀ aryl group and C₄˜C₃₀ hetero aryl group.
 38. The organic lightemitting diode of claim 35, wherein at least one of the lower emittingmaterial layer and the upper emitting material layer includes a firstemitting material layer including the organic compound and a secondemitting material layer disposed between the first electrode and thefirst emitting material layer or between the first emitting materiallayer and the second electrode.
 39. The organic light emitting diode ofclaim 38, wherein at least one of the lower emitting material layer andthe upper emitting material layer further comprises a third emittingmaterial layer disposed oppositely to the second emitting material layerwith respect to the first emitting material layer.
 40. An organic lightemitting device, comprising: a substrate; and the organic light emittingdiode according to claim 9 over the substrate.